Holy Priest
For each talent point spent in the Holy tree, the priest also gets:
Healing – Improves your healing by X%.
Meditation – Improves your mana regeneration from Spirit in combat. This would likely replace the existing Meditation talent from the Discipline tree, which many Holy priests consider to be a "must-have." Regeneration will also probably be determined by whether you are in or out of combat, and not the "five-second rule.
Radiance – Adds a heal-over-time effect to direct heals, such as Flash Heal. Mastery on gear would boost this bonus, and no other talent tree would grant it.
Discipline Priest
For each talent point spent in the Discipline tree, the priest also gets:
Healing – Improves your healing by X%.
Meditation – Improves your mana regeneration from Spirit in combat. This would likely replace the existing Meditation talent.
Absorption – Improves the amount of damage absorbed by spells such as Power Word: Shield and Divine Aegis. Mastery on gear would boost this bonus, and no other talent tree would grant it.
Frost Death Knight
For each talent point spent in the Frost tree, the death knight also gets:
Damage – Improves your melee and spell damage by X%.
Haste – Improves your melee Haste by Y%. This might allow us to remove some of the Haste in the Icy Talons line of talents.
Runic Power – Improves the rate of runic power generated by abilities. While all death knights want runic power, Frost death knights would generally have more runic power than Blood or Unholy death knights (who would receive a different benefit from their respective trees). An Unholy death knight who sub-specs into Frost would still be able to benefit from this bonus, though because they're investing fewer talent points, they'd benefit to a smaller degree. Mastery on gear would boost this bonus, and no other talent tree would grant it.