3g without powersaving and the battery will last about 3 hours.

Mind, some people run so much crappy IM stuff that 3 hours is already the case...


Operators define thresholds for 3g, in the form of "X bytes in Y seconds: upgrade to hsdpa", "less then Z bytes in A seconds: downgrade to wcdma", and also minimum active times.
The minimum active time is annoying, as that means that things which use a low level, but frequent network access can keep the 3g on full tilt continously.