This afternoon Tseric posted a surprise in the warlock forums - the the functionality of the skill life tap (which converts health into mana) will be changing in the next patch - to be modified by +spell damage gear. Rank 3 and higher of the spell will now benefit from 80% of your spell damage gear (it's unclear as to whether it will benefit only from +spell damage, or whether it will benefit from +shadow damage), meaning it will both give more mana and take more health. As a warlock myself, this will take a bit of getting used to, as a loss of 400-ish health (which is spammable when necessary) becomes a loss nearly twice that - ouch! However, the reaction on the warlock is overwhelmingly positive (aside from the occasional query "But what about Dark Pact?").