As of now Sony Xperia Mini Pro have received official Android 4.0.4 or Ice Cream Sandwich. Sony has now released the upgrade to all their Xperia 2011 devices which is a really good move and will still give its potential customers to opt for their phones. This is not something we see alot especially with Android phones but indeed a wise move- by doing this all the Sony phones in the medium budget range has ICS .
To upgrade just install the PC Companion from here and follow the on screen instructions.
Custom ROM users- Now there are ROMs with proper accelerometer since the developers got hold of the official kernel . Check here at XDA for some awesome ROMs.
MIUI for Mini Pro/LWW/Mini http://forum.xda-developers.com/showthread.php?t=1578109