OSX and Longhorn are going to do it. Now Xorg is going ahead with a GL based window manager. You can check out some info on it here and here.
I remember threatening to do something like this a while back, but didn't because: (1) I don't want to run linux as a desktop yet, and (2) can't be bothered to learn OpenGL. That kind of limited me.
I've always felt that the massive parallel math power of GPUs should be harnessed even when not playing games. It seems like those logic gates could be repurposed to provide anything from encryption to video encoding. Acclerating the various graphical filters in hardware is only the beginning.
Remember there was a general C based programming language for GPUs that was announced a year or so ago by nVidia, called Cg. It's designed for writing procedural shaders, but should be able to be generalized to other data processing as well.
Cg sample code:
cg.LoadImages("C:\My Documents\My Porn");
I think I read somewhere that the PS3 was going to use Cg for game development.
I'm surprised we haven't heard anything about Tiger acceleration on the Mini. It is still an open issue, even though the betas of Tiger are getting really close to the final version.
I've read in many places that it doesn't have the CPU/GPU horse power or video ram to run in the new 'cool' core image mode. Basically you will get the same experience you do today. But I guess you won't know for sure until Tiger is released.