Ok, so there alre already a few threads about battery problem. Unfortunetley most of them misleading - some of them suggesting battery drains fast because of the multitasking. It is not true. First of all multitasking isn't responissible for battery drainage, as it is not real multitasking - apps doesn't run on background, so they can't drain battery). Second of all, wifi is to bo blame. On previous iOS firmwares wifi was automatically OFF whenever the device was locked. Since iOS 4.0 wifi stays ON all the time, even when you lock your iPod touch. This causes dramatic battery drain, as it is constantly communicating with servers. My iPod touch 3rd gen 32gb drains about 30-50% of battery overnight when locked with wifi ON. Yesterday I did some different test - set wifi to OFF for the whole night and guess what battery percentage didn't drop by even 1%! Regardless of how many apps were opened in multitasking. Concluion is - Apple neeeds to go back to shutting wifi OFF when device is locked - or at least give this as an option switch in the menu.