I found a link to Mashery on TechCruch. It is an interesting service, the idea is that you expose your API to the world through the Mashery system and they take care of some of the higher level functions like traffic analysis and developer key provisioning. Organisations that use Mashery will be able to skin the system to look the way they want.
The Mashery infrastructure itself looks like it is built on top of the S3 storage system at Amazon and their EC2 elastic compute cloud so in theory they can scale out pretty quickly. All in all it is an interesting play for the Web 2.0 infrastructure space which is more interested in exposing data and behaviour than the actual metal it sits on.