I was just searching the market this morning, bored at work and came across this. What it does it turn off the data connection while your phone is asleep and every 15 minutes, turns it back on to get texts and push notifications and everything. Ever since this last update, my Thunderbolt even had worse battery life, even on 3G (lasted about 10-11 hours max), didn't try a full battery on 4G but it went down a lot quicker, guessing around 6-8 hours max. Anyways, downloaded it around 5 am this morning and after 8 hours my battery (always on 3G) is still at 50%. Pretty nice!