The 329 item level is the minimum (emphasis on MINIMUM) gear level required for running heroics. If you can't keep up, gear up. There is plenty of quest items, regular instances, crafting, reputation, and auction house pieces you can acquire before complaining that you can't keep up in heroics. Cataclysm has been out for 4-5 days now; you don't have all of that yet.
There are many guilds clearing the 25-man raid content within this first week of Cataclysm. They didn't do that with just tanks and dps. They obviously figured out and adapted to these changes without much issue.
Cataclysm isn't the stack-haste-whack-a-mole that was WotLK. You have a limited mana pool, and should be using it accordingly. People should not be dying if you have mana (but you aren't going to keep the party alive healing the DPS drooling on himself while standing in the fire, nor through the boss mechanics designed to be avoided/prevented). If you are running out of mana, here are a few suggestions.
1.) Gear up from the previously mentioned non-heroics options
2.) Enchant/gem/reforge for intellect/spirit
3.) Buffs - There is a reason elixirs/flasks/well-fed and potions are in the game - use them.
4.) Look at the dps of the group, are fights lasting longer than they 'should?' (i.e. - that's a dps problem not a healer problem)
Once people are sitting in Tier 11, most of these 'mana issues' will go away.
WotLK created a lot of bad healers, and with Cataclysm, you will need to learn/relearn how to be a good healer, or you can enjoy the 45+ minute and climbing queues as a dps.
You don't hear the good healers complaining; Heroic healing is fine, deal with it.