[Update]: Okay, this appears to be how it will work:
Certain skills with very common usage in a spec, such as Crusader Strike for Ret and Holy Shock for Holy, will have a secondary effect. This effect will buff you with one application of Holy Power, up to a maximum of 3.
The Holy Power buff will probably then give you a spec-specific boost, for example it might increase your Holy Damage by 1/2/3%. This in itself isn't too fun, it would just be providing a Vengeance for all three specs, but that's not the entirety of the mechanic.
Holy Power stacks can be consumed (entirely) in order to cast specific new abilities, or boost existing spells. The effectiveness of these abilities would be proportional to how big the stack was, making sensible timing imperative.
Significantly, in the same way that Seal of Vengeance has a ramp-up time for PvP balancing purposes so would all the Holy Power spells. This adds scope for new abilities and talents with dynamic durations that would require you to engage first, for example adding an interrupt talent to Ret that needs Holy Power, making fine tuning balance a far easier proposition.
Done well, this new mechanic would add another layer of complexity to a class notorious for its' faceroll approach. No bad thing.
Just outlined on the Blizz developer chat:
Q: What is the goal when re-designing the paladin class? How do you plan to change rotations, talents, etc?
A. All of the paladin specializations will make use of a new resource called Holy Power. Holy Power accumulates from using Crusader Strike, Holy Shock, and some other talents. Holy Power can be consumed to augment a variety of abilities, including:
* An instant mana-free heal: Word of Glory
* A buff to increase holy damage done: Inquisition
* A massive physical melee attack for Retribution paladins: Templar’s Verdict [Templar's Verdict? Ace name!]
* Holy Shield’s duration is now extended by Holy Power
* Divine Storm’s damage is now increased by Holy Power
We also introduced several new heals for Holy Paladins including Healing Hands (an AoE heal-over-time that is applied to all players standing near the paladin), Light of Dawn (a cone heal with a 30-yard range), as well as a new heal called Divine Light, which is similar to a priest's Greater Heal, and the new instant heal mentioned above, Word of Glory.
This sounds suspiciously like 'our' Runic Power, essentially an auxiliary resource for additional effects. Potentially it would be a huge shake-up to the class, but it may well be a bit more than can be balanced during a Beta phase. Remember though that this is Beta. Early Beta. Everything is subject to change.
Oh, and they need to call it something else. I'm tempted to say "Awesome", but whatever the name I'll henceforth refer to it as just "the Jong Meter".
More on Templar's Verdict and Word of Glory:
Q: Can you give us a sneak peek at one or two of the new Retribution abilities or talents?
A. Templar’s Verdict: An instant weapon attack that causes a percentage of weapon damage. Consumes all applications of Holy Power to increase damage dealt:
1 Holy Power: 55% Weapon Damage
2 Holy Power: 125% Weapon Damage
3 Holy Power: 225% Weapon Damage
Word of Glory: Consumes all Holy Power to heal a friendly target for a specific amount per application of Holy Power (0 mana cost, 0 cooldown, instant cast).
So the resource won't be a continuous 1-100 'meter', rather a self-buff in the style of Vengeance which will be consumed when a particular spell is used. Call it a cross between Runic Power and Soulshards I suppose.
The final word on Judgements is Wisdom is dead, Light and Justice are being baked into the same spell:
Q: If Judgement of Wisdom is being removed from the game, are paladins getting a new Judgement so we don't all have to use Judgement of Light?
A. There will only be one Judgement spell. This spell places a single debuff on the target with the effects currently associated with Judgement of Light and Judgement of Justice. The Judgement of Wisdom effect has been retired completely.