Every since "upgrading" my 2nd generation iPod Touch to iOS 4, it seems to lose power overnight (when not plugged in). What can I do to fix this? I have tried a restore and that did not work. Seen as a problem in releases iOS 4.0.1, 4.0.2 and 4.1
If you don't need any network activity, I would recommend enabling Airplane Mode overnight.
Failing that, disable bluetooth and/or wifi if they are unnecessary
Disable as much Spotlight search as you can afford to by going to Settings->General->Home Button->Spotlight Search.
You should wait until Apple releases iOS 4.1 that should improve overall performances on old iDevices, like iPod Touch 2G and iPhone 3G.
You may want to check any applications running in the "multi-task" mode. I had a issue with my iPhone 4 dieing quickly when I had certain apps still trying to queue the network. Good luck!
I have an iPhone 4 and went through this issue with Apple Genius Bar guys and Level 2 support over the phone. The conclusion was the when a contact is modified on the iPhone/iPod in an Exchange account (like Gmail) the device gets into and endless loop trying to update the remote database. It stops only when finally the device is connected to a data plan or wifi connection to the server to be updated.
Strangely enough the issue is only with contacts, not with calendar or mails. It was discovered with 4.0 and it is still valid for 4.3.3.