+1 on this one.. really improves battery life.. and if you pay for it you can have it turn data on periodically so you don't miss emails.. i'm wondering though, will it still push things like with yahoo messenger? or skype even? use them for work and whatnot so havent really had a chance to test it..
Edit: works with the messengers.. Bought it
and Edit Edit: took it off the charger yesterday at 3.. yahoo running.. 79% in 18h33m.. estimated 1h32m left.. it has been idle though overnight since around midnight though.. either way.. awesome app.. no downside so far..