And I guess to be clear my point of this thread isn't whether the Pi is worthwhile-- just if it is cab-ready yet. Sure, I can find or piece together a used PC for a similar cost, but as somewhat of a noob I like the fact that it is a standard... if someone else can get MAME running well on a Pi, and posts "for dummies" level directions that I can follow, then I can get it running, too. No BS about what processor I am running or graphics card or if the old hard drive I am using is going to fail in a week. I love the fact that there is a massive group of rabid programmers developing for the exact same hardware configuration I can order on Element 14, etc. And even though the hardware is standard, it is still a computer, so there is the possibility of, for instance, a customizable front end, unlike a 60-in-1. Also, the big thing for me (again, in concept, I have yet to get hands-on with one) remains the composite out. I can think of all sorts of gaming and visual art-type things I could do with a Pi and an old CRT TV. The $35 price point sure welcomes experimentation.
I guess that is why I am excited about the possibilities.