Here's some more leaked info on the rumoured X3:
Sony Ericsson Xperia X3 - Latest Mobile Phones
Sony Ericsson Xperia X3 Android phone leaked - The UK Mobile Phone Blog
WM 6.5, new interface
also Xvid support, flash support,
seems also it runs much faster and smoother.....
Improved keyboard and reworked navigation cluster....
Well, it's not little....
I mean new platform would me great but
seems not many devices run it these days.