A notion I want to make about battery life, what I found out over the last days:

3G data connection idle (connected, but not transferring) uses about 40mA -> battery would last 35h in idle.
2G data connection idle (connected, but not transferring) uses about 10mA -> would give about 6 days idle!
WiFi connection idle (connected, but not transferring) even less than 10mA when in good reception range -> also about 6-7 days idle.

"Allow background connections" disabled, no automatic feed/mail/etc updating in background (though twitter updates still work automatically, strange) -> normally no automatic connection established and if established manually by browsing, etc. after half a minute of inactiveness, the connection automatically closes itself again
--> this is about 5-10mA in idle, could give you up to 10days idle in theory... However, no automatic background updates is somewhat of a bummer to me in a smartphone :-P

So if you want to last your battery as long as possible, use (good reception) WiFi or 2G (GSM) whenever possible/bearable for you.

Not taking into account in the figures above is of course active usage... If you play around with the device all day, you drain it in one single day easily still...