I've noticed my battery has been draining much faster since successfully upgrading my 3GS to 3.1 using Pwnage Tool. Baseband is still at 04.26.08. I always set up as a new phone, and have never noticed battery drain issues until the 3.1 upgrade.

Ultrasn0w works fine - even though I don't need it because 90% of the time I'm using a legit carrier sim - apart from the battery drain issue. I left my phone over night in airplane mode and the battery drained ~ 20%.

I've removed Ultrasn0w and now my battery is fine.

Anyone else experienced this?