I could be remembering wrong but with the 360 we knew there were contracts with ATI and IBM but it really was the block diagram (that turned out to be correct) leaked and published by TeamXbox that got the ball rolling which really set legit parameters for what we were looking at.
Worth noting that schematic came out according to my google-fu as early as February 1st 2004, and thats just what I could find. Close to two years before the 360 actually released. Although, I dont think i initially believed the schematics back then and I'm sure I'd doubt any that came out this time for a while.
Worth noting for timeline purposes imo, with a lot of gaffers still nonsensically thinking 720 is going to come out in 2012 (though at least even that nonsense finally seems to be sinking in to them that it's not happening).
I'm starting to realize along with some others there really may be something to this MS kiboshing used games thing. It would probably be pretty ginormous if they could pull it off. I've never been a big used game buyer (I figure for 5 bucks difference I'd rather have the pristine new copy by far anyway, on new-ish games) but I did pick up Killzone 3 used recently, for older games its a pretty good value and i bet a lot of people do it almost exclusively.
My initial thought/worry would be if they ban used it will just push more rampant piracy perhaps. I'm not so sure though. Publishers would love it and might be inclined to support the Xbox more than other platforms.