It looks like there's a lot of overlap with the feature set you need, as well as the advantage of some extra documentation + testing. It's a Python WSGI app, instead of Sinatra/Rack, and the data over the wire is encoded as Atom, but there could be some useful lessons to work from at least.
http://code.google.com/p/pubsubhubbub/
It looks like there's a lot of overlap with the feature set you need, as well as the advantage of some extra documentation + testing. It's a Python WSGI app, instead of Sinatra/Rack, and the data over the wire is encoded as Atom, but there could be some useful lessons to work from at least.