This news seemed too big to neglect mentioning: Official word on changes to Combat Resurrections in Cataclysm.
This is quite a big and interesting change for the use of combat rezzes in Cata (and in live currently, as these changes do seem to be in effect judging by attempts to BR during a run I was in last night).The design for combat resurrection effects has changed a good deal for Cataclysm, and we want to make sure players are clear on how spells like Rebirth and Create Soulstone now function. Rebirth has a 10-minute cooldown and Create Soulstone has a 15-minute cooldown. On raid boss encounters, you can only use one of these combat resurrection spells (so one Rebirth or one Soulstone) per attempt for 10-player raids. For 25-player raids you can use three forms of combat resurrection per raid boss attempt (so three of any combination of Rebirth and Soulstone). The count is incremented as soon as a player accepts a resurrection, so one can always choose not to accept if he or she wants someone else to get the resurrection instead. There is no equivalent of the Sated debuff (which tracks Bloodlust/Heroism usage), but you will get an error message if you try to resurrect too many players, and we might add tracking to our raid interface if there is demand for it. Outside of raid content, you can use as many battle resurrections as you have available. (source)
Essentially, battle rezzes are now being limited per attempt (1 for 10 mans, 3 for 25 mans). The shorter cooldown (10 minutes) for Rebirth is likely to ensure the cooldown doesn't interfere with multiple wipes/attempts within a short period of time. I imagine this was to stop not necessarily stacking druids in a raid, but preventing BRs being used as either a strategy or a crutch in downing encounters. This will certainly make effective communication and timing of BRs critical, as well as debating whether you want to rez someone or to save the rez in case it's needed later.
The biggest thing I think this goes along with though is the whole changes Blizzard seems to be aiming for with Cataclysm: Gone are the days of mindlessly ploughing through content without worry of using CCs, AEing mobs down, and not worrying about raid damage or healer mana or people dying because they can 'just be rezzed'. The biggest thing I've gotten out of beta raids so far is raid awareness is crucial - raid members will need to be paying attention and doing more than just spamming 1-1-2 or whatever their rotation may be. Raid members need to be mitigating the damage they take, avoiding damage, quick on stuns and CCs, and working together to get bosses down. No one can rely on unlimited healer mana or combat rezzes anymore. Should make for more involved gameplay I think! I'm genuinely looking forward to all the changes (though less enthusiastic about pugging things), as so far everything is shaping up to be very fun in Cata!