Other than the Xperia, the only thing I've seen from HTC is software. There was a leaked piece of software that replaced the built in contact management and messaging apps, making them very pretty and finger friendly.
All the graphics within the leaked software was for VGA resolution screens. The speculation is that the next generation of devices will be very similar to the current ones, but with VGA screens and actual hardware video acceleration meaning fully graphical interfaces will be very slick and fluid, they can effectively build a Direct3D interface for everything.
The only other adition I can think of for them to squeeze in is WiMax, but no Uk carrier has gone that route yet, so that could be a US only feature.