Ok,
So I jailbreaked and installed ultrasn0w on my iPhone4. But my battery is getting pretty hammered. I lost over 20% in 7hrs of standby, with wifi off, 3g off, bluetooth off, push off, almost everything off.

Is anyone experiencing this?

Thanks,
Abras

My co-worker had the same issue, after installing the jailbreak though, before the unlock. His battery drained on the iPhone 4 very quickly, rebooting didn't help. Once it had drained entirely and he re-charged and rebooted he had no problems and hasn't since.

Mine came after unlock. At the moment Im losing ~5%/hour in standby. I already fully recharged and nothing happened. Im at 4.0, will restore it tonight to 4.0.1 to see if it gets better.
Thanks

What have you installed after jailbreaking besides the unlock?

Double click on the HOME button and turn OFF everything....HUGH battery Drain issue.....

I have been experiencing the same problem and I noticed I always had a constant data connection when looking in sbsettings (Data ip always had an ip in it) and then I realized FaceTime keeps trying to activate, when I turn FaceTime off data connection gets cut but I loose data entirely and MMS and turn it back on data works again but it’s still trying to verify, anyone have sbsettings too look and can verify or maybe its just me

*Need to reboot after you turn it off to notice data won't work but again might only be on my end

Same issue here, I`m still on ATT unlocked to prep for Euro trip, battery drained like crazy last night. I removed ultrasn0w just now to see if it gets better. on 4.0.1 and it was perfect after jailbreak.

Ok, did some testing and there is something really weird going on here. Put my phone in Airplane Mode, and then let it stay in stand by for an hour. It lost 5%. Its too much! I ll drain the rest of the battery, will wait couple of hours, then will charge it and restore to 4.0.1 and see what happens.

I have same issue.
Check out 'Settings -> General -> Usage'.
And, look at both 'Usage' and 'Standby' fields.
They always show the same period, even I have not used my iPhone 4 whole time after full battery condition. This is really strange.
I guess some processes reject standby mode in spite of turning on standby.

I am having the SAME problem....when I had my iphone 4 jailbroken...the battery life was fine....after the unlock....I lose about 5% every hour while in standby...That too...with no push notifications....no other apps installed...in airplane mode....brightness less than half....3G off...data off.....I have restored 3 times, and same issue everytime. I hope there is a fix for this....if anyone knows, please post! Thanks