The current line-up of Xperia handsets from Sony Ericsson may never get the Android 2.2 officially, but this has not stopped the developers at XDA forums to support the phone. The biggest member of the Xperia family the X10 got its Android 2.2 based custom ROM quite a few weeks ago.
Now, three of its smaller siblings the Xperia X8 and the X10 Mini/Mini Pro have got their share of Android 2.2 based custom ROMs. The ROMs for all the three phones mentioned above are based on Android 2.2 with HTC Sense UI on top of it. These ROMs have been ported to these smaller Xperia siblings from the HTC Hero and Legend. Kudos to the developers for all their hard work!
However, not everything works at the moment. In most of the ROMs, the camera functionality is broken along with some Bluetooth and media playback issues. Nevertheless, the developers are hard at work and are churning out new updates with every passing day.
Hopefully, these issues will soon be fixed by the developers and all the members of the Xperia family can get their share of Android 2.2 love, unofficially. X10 Mini owners should head over to this thread while X10 Mini Pro and X8 owners should head over to this and this thread, respectively.