I'm currently looking at services for this as well,
just found encoding.com from an answer to this question
I also have been looking at CDN's becuase I also need to ensure that the videos don't overwhelm my servers, not sure but I thought some of them said full service media including transcoding. if you need a CDN to deliver the video too it may come with transcoding.
Now I'm getting into server stuff, maybe this should topic should move to server fault?
