Mana regeneration was a much-discussed area for change in patch 3.1, but when the patch went live, it turned out the changes hadn't been all that massive; most healers are still not putting a high premium on regen stats or watching their mana bars too closely, fights like Vezax excluded.
A big part of the reason why mana regen has been so extreme in Wrath is Replenishment; as of right now, any of five DPS specs (Shadow Priest, Survival Hunter, Retribution Paladin, Frost Mage, and Destruction Warlock) will provide the ten lowest people in your raid 0.25% of their maximum mana per second. Among other things, this makes Intellect a prime regen stat.
Well, Replenishment is getting a bit of a nerf in patch 3.2: instead of 0.25% max mana per second, it'll be 1% maximum mana over five seconds. That's a 20% nerf. This applies to all sources of Replenishment. At the same time, all items with MP5 on them are having the MP5 buffed by about 25%. These two changes will probably even out for the MP5-based healers (Paladin and Shaman), while making them value MP5 gear a bit more. Druids and Priests will feel a regeneration nerf, but I think they can afford it.
Patch 3.2 will bring about a new 5, 10, and 25 man instance to WoW, and usher in a new 40-man battleground called the Isle of Conquest. WoW.com will have you covered every step of the way, from extensive PTR coverage through the official live release. Check out WoW.com's Guide to Patch 3.2 for all the latest!