As reported by Tricia Duryee, AllThingsD:
The site is a resource center that links to a growing list of 15 to 20 vendors and agencies that can help with all aspects of building a mobile site. The site also has an emulator that shows how your site looks on a phone and case studies from companies.
The initiative is awesome, and is a smart way for Google to promote the mobile ad business as well. But, I think mobile website has a negative connotation of being stripped down. Better mobile sites are ones that maintain the content on the phone and web in a consistent way — like the Boston Globe (there is a consistent look and feel that dynamically changes with resolution).