I just found out about the ION platform a couple of days ago. (I know: I'm out of the loop. I've been so concentrated on, and disappointed by, the Intel G45--specifically the mini-ITX board--that I didn't know something like this was on the horizon.)
This thread has been following the ION:
Official NVIDIA Ion Thread, though nothing definite has come to light on availability for HTPC builds. The
ION-like Mac Mini is available now, but that's about as close as we can get right now.