Sony Ericsson patched the ability to root an Xperia X10 in the latest firmware update release (2.0.2.A.0.24). The guys over at xda-developers worked around this by releasing pre-rooted versions of the new firmware. However, there is now a fully-working root solution for those who had already upgraded to the latest firmware.
The method uses SuperOneClick (v1.5.5) and it is as easy to apply as the Z4 Root method. Download this file from xda-developers, make sure your handset is in USB de-bugging mode, connect your handset to your PC and then run the program. It’s as simple as that and should take less than a minute to do. We had to manually restart our handset before we had SuperUser permissions though, so make sure you do that if it doesn’t happen automatically.