I am writing this so that at least me can remember what I did to root to phone. Well, after installaing the 2.1 update on my xperia x10, I just noticed that I had to reinstall all my apps (30+) one by one, and moreover, every app data was lost; all this although i did a backup with appInstaller. Also, the market was not showing my apps, so no more auto-checks for upgrades and so on. After researching, I saw that Titanium Backup was able to do all of that and much more. That’s when I decided to root my phone (Titanium requires root access) and have Titanium functional. Here’s how you can root your xperia x10 2.1 (and probably 1.6).