Announced by Sony Ericsson, there will be a software updating coming very soon to your Xperia X10 phones.  When the updates get pushed. you will see a notification on your xperia x10 asking if you want to update.  The easiest way to get the new software is to accept this update - you can use your mobile network connection or a WiFi connection for the download. Alternatively you can update your phone using your PC - please visit www.sonyericsson.com/update and follow the instructions.

Here what's the update will do:

This update focuses on improving the general performance, speed and responsiveness of Xperia X10. For example, there are speed improvements in messaging tasks and camera UI. In addition we add a free back up and restore application so you'll never lose your settings and information. In selected markets, PlayNow with premium apps and games will also be added.

source: http://blogs.sonyericsson.com