Aggrieved user - did you ever find out what caused this?
Im using HTC Desire HD on Three. Have 1GB per month limit.
Since I got my phone 4 months ago, always used less than 500mb/month.
However, since my android version updated to Gingerbread, sudenly I'm averaging 50 mb/day but I'm not doing anything differently.
Can't find anyone else complaining about the sudden jump in usage until I saw your post. I have spoken to 3 who suggested a task killer to stop apps accesssing the internet so much, however this has had little or no impact.
I have tried the Spareparts suggested by others, however it says that Gingerbread ROM does not contain battery stats.
Please help someone, at the moment I am having to turn my mobile internet connection off at the end of the billing period to avoid getting ripped off.