Come tomorrow (December 5th), the new Burning Crusade talents will be in the game. Some classes will see a big change in what they can do, some not so much.

The paladin has always been a popular class, but it has suffered from lacking DPS. This has often meant it has been relegated to a support role. If you played the class the way it was supposed to, this didn't matter, since it is the best support class in the game.
With the new talents and spells, paladins have become much more capable in their lacking areas; tanking and DPS'ing.

New spells
Seal of Blood: Blood Elfs get a new seal, which deals 35% of weapon, but deals 10% of the damage caused to themselves. It's decent, but not great and other seals will give better results (SoCo for 2Hers, SoR for tanking). The seal can be judged for ca. 310 damage at the cost of 33% of the damage to yourself.

Seal of Vengeance: Alliance get a new seal as well. The seal has a chance to proc a 12 second 10 DPS DOT that stacks 5 times. Great for fast tanking weapons, not so much for 2Hers where SoCo still rules. It can be judged for 120 damage per application of the DOT, so a potential of 600 damage.

Crusader Aura: Increases mounted speed by 20%. It's an aura, that makes you ride faster. It's good for what it does :)

Spiritual Atunement: Passive ability. Gives you 10% mana of the amount you are healed; eg. you are healed for 2k, you receive 200 mana. Great for tanking, since you will be using your blue "rage" bar for that purpose :)

New talents of note
Holy:
-Sanctified light and Light's grace: SL increases crit chance for Holy light by 6% at 3 points. Combine this with LG (which reduces cast time of next holy light spell by 0.5 seconds if cast within 15 seconds) and you have solid 2 second heal that has a high crit (11% with all talents, even more with INT).

-Holy Guidance: 35% of your INT to extra +heal/+dam for 5 points. It's a very, very good talent. A reasonable INT at 70 would be around 600-700. That's around +200 damage/heal. That's a lot of damage, so holy is defo a PEWPEW build now.

-Divine Illumination: Reduces mana cost of all spells by 50% for 10 seconds. It's nice for DPS'ing, but not so nice for healing. With DPS'ing you benefit from throwing all your DPS spells back to back, but not so with healing. With healing, if you are in situation where you can get away with spamming your big, mana-expensive heals without over-healing, you are in a critical situation and mana is your least concern. Throwing heals back to back, it will still only save you around 1200 mana, so not overwhelming for a 41 point talent.

Protection:
-Improved Righteous fury: Decreases damage taken by 6% and increases threat by 50% with RF active. This means 60% more threat with RF active. If you want to tank, this is a must have talent. And even if you don't plan on tanking, 6% less damage for 3 points is good.

-Reckoning: 10% chance to gain an extra attack on next 4 swings within 8 seconds when damaged in melee. It's decent, but should really be a 3 point talent IMO. 5 points is a bit too much, but take it to fill out the tree.

-Ardent defender: When below 20% health, damage is reduced by 50%. In effect this means a doubling of health, when below 20%. Again, it's a good talent, but it would be much better off at 3 points. And you really shouldn't be below 20% health when tanking. Leaves room for some error, but with a decent healer, it's territory you shouldn't be travelling :)

-Avenger's shield: The Captain America attack. 30 yard range, decent damage (650-ish) and affects 3 targets. Good for pulling and/or for runners. However, it has a high mana cost and a 30 second cooldown. For a 41 point talent, it isn't impressive, but you might as well get it, if you are up there.

Retribution:
-Sanctity Aura: Increases holy damage done by party by 10%. This is good for a 40/21 *holy/ret PEWPEW* build. Improved sanctity aura increases healing done to party members by 6% for 2 points. Imp. SA is decent and worth the points if you are going deeper in ret anyway, and it's nice as a courtesy to the party healer :)

-Sanctified Crusader: Judgement of Seal of Crusader will now give 3% crit chance to other people hitting it as well. If you are DPS'ing you would probably judge crusader anyway, so 3 cirt chance to you and the rest of the party is nice. 3 points is a bit much, 2 points would have been better, but it's still a good talent.

-Sanctified judgement: 100% chance to have judgements return 50% mana. Eg. half price for judgements for 3 points. 2.5% of base mana instead of 5% of base mana. At 6k mana and spamming judgement every 6 seconds, this would save you 1500 mana per minute. With judgements every 4 seconds, you would save 2250 mana per minute.

-Crusader strike: Instant strike that causes weapon damage + 40% of your holy damage. 10 sec cooldown. A very good talent, and it should be since it's a 41 point talent. It's instant (good), causes weapon damage (good with a 2H, which you should be DPSing with anyway) + 40% of your holy damage (not so good, since we aren't PEWPEW'ing now, so we would have preferered STR or AP, as that increases our overall DPS more through base damage than +dam gear does). But it's still a very good top-talent and the reason to spec ret.

Builds
Below are some suggestions and tactics for various builds.

Healing:
Support machine - http://www.wowhead.com/?talent-bc=sVxubgzGestVMuc
Sacrifices some soloability for BoK. Focused on Healing light as main heal.

Solo friendly build - http://www.wowhead.com/?talent-bc=qVxubgzGeotZV0tt
Goes in to ret to get SOC and 5% crit to be able to farm a bit without dieing of boredom.

Spot heal with Flash of light, main heal with Healing light.

Tanking:
Full on tanking - http://www.wowhead.com/?talent-bc=aZVhxIghzxzEoV0ez
This is for main tanking and you will need a healer for this. You can solo well with this, since you have a bit of ret in it, but since you aren't in holy at all, the most you can do in a group is second off-healer.

sub raid lvl main tank - http://www.wowhead.com/?talent-bc=aVxhZVhtIghzxzEo
You can still tank well, but you are missing a bit of ret to make it shine like before. You can however off-heal now and heal your self in a tight spot (which also generates agro if you are tanking).

Pop righteous fury and throw on aura of choice (devo or ret), throw your shield, consecrate, judge Seal of the Crusader on main target, slap on seal of vengeance/righteousness and keep up consecrate. You are now tanking and making warriors cry. Congratulations.

DPS:
full ret - http://www.wowhead.com/?talent-bc=aZxGkh0hZVbxt0cuVIot
Full DPS build with the ability to off-tank in a tight spot. Most of the yellow damage comes from crusader strike and SoC judgements on stunned opponents. Use a 2H'er for big SoC procs.

PEWPEW - http://www.wowhead.com/?talent-bc=qVxhbgzGtoxZVfot0cz
Holy build with a dip in to ret for SoC and sanctity aura. Your damage will come from Holy shock and, when applicable, exorcism and holy wrath. Another bonus from this build is its ability to heal very well. The only thing holding it back from a "real" healing build is only 1 point in "Light's grace" (which is only a matter of 0.5 second of your healing light. No biggie) and Divine illumination (suck a pot instead). Instead you get sanc aura for another 10% holy damage.

Sanc aura, judge crusader, spam holy shock/exo/HoW/crusader strike and judge SoC/SoR(for non-stunned opponents) when you can. Voila, DPS :)