If you are a fan of HTPC, MiniITX or other SFF designs, you'll probably be interested in AMD's DTX spec. Designed as an extension of ATX specifically for small form factor machines, AMD is soliciting for vendor support and feedback on various guidelines to craft systems by. The references include things like motherboard size, I/O connector positions and the like. Likely, with AMD and Intel going head to head with Viiv and Live (though neither is doing well at the moment), they'd like to be seen as an innovator in the mini-PC market.
They face fierce competition, from companies like Apple and Via, who are already infamous among the mini-PC crowds.