I just discovered the reason why TimeMachine was backing up so much data. I forgot to exclude my Maven and Ivy repositories :o)
Here is a good tip to discover which files are backed up. You need to have the Developer Tools installed.
When TimeMachine backs up
- Launch /Developer/Applications/Instruments
- Select File Activity
- Open the default target combo box and attach the backupd process.
- Start recording
- Enjoy the list.
I wish there were a less geeky solution.