Ok, I appologise for saying you were spamming, but you should just post those links off the bat. As for what it will be running, everyone says it will run 3 3GHz PPC chips. But I don't think they realise thats crazy talk, or at leaste I believe it is.
The alpha/beta kits were Powermacs: developers have been getting final hardware dev-kits over the last few weeks.
For fixed platform such as a console, 512mb or RAM is more than enough: the current xbox only has 64mb which is part of its UMA (unified memory architecture) meaning that 64mb is split between the graphics processor, sound chip etc as the developer sees fit.