Android 2.1 Eclair update kit for SE Xperia X10 Mini is already out in most parts of the world.
On top of the OS upgrade, the kit will bring the following improvements --
• Improved Bluetooth functionality with support for receiving and sending contacts, pictures, and more
• New backup and restore application plus extended content back up
• Automatic synchronization of contact pictures between your phonebook and Facebook
• Improved ways of handling audio, text, numbers, and pictures in your messages
• Autofocus on Video Capture
If you're still stuck with Android 1.6, then you might want to check if Eclair is already available for your device and perform the upgrade. Here's how you do it --
1. When the new software is available for your SE Xperia X10 Mini, a notification will appear in your phone's status bar. You also get the same software availability notification when connecting to PC Companion.
2. Download and Install PC Companion on your PC.
3. Connect your phone to your PC.
4. Start PC Companion
5. Follow the upgrade instructions.
Need PC Companion? Get it from this link.