I have very similar hopes for a media streamer, and have been looking at it myself for some time. I only recently retired my Boxee Box (which is still the BEST in terms of the automatic scraping you talk about - but can't handle HD audio) and right now am using a WD TV SMP temporarily. The UI on the WD is just too slow, and the movie selection process isn't what I was looking for.
If I had to buy one box today, I think I'd go with the Mede8er 600X3D. It has a lot of positive buzz here and I like its feature set. But everything halfelite describes is pretty much where things stand right now. Nobody makes exactly what both you and I are looking for. A box that will play most formats, can handle HD audio, and has a great, built-in scraper and movie wall.