If you didn't update your Xperia X10 smartphone to Android 2.1 from Android 1.6 you really should...
Some of the new features in Android 2.1 "Eclair":
- HD video recording, 720p MPEG-4 (only X10)
- Send files via Bluetooth™
- Set up multiple Google™ accounts
- New Back up and restore application
See the support page on Xperia X10 website.