If the recent update to 1.1.3 didn’t do it for you, you can revert your iPhone to version 1.1.1–as long as you don’t need to make a call.
The guys over at IntoMobile have posted a rather convoluted process to downgrade your phone from firmware version 1.1.3 to 1.1.1. Unfortunately, the downgrade breaks the iPhone’s ability to make phone calls. On the flip side, version 1.1.1 of the firmware is jailbreakable and can run third party applications.
There’s rumored to be a 1.1.3 jailbreak out there, but the team that created it won’t be releasing it until February. If you simply can’t wait, this might be an option.