Recess has been in development, full-time, for about 3 months now. It all began after returning from the Web 2.0 Expo in New York - reinvigorated about the pragmatic utility of PHP by Cal Henderson (I now refer to his talk as my PHP Tent Revival) and inspired by DHH and others about the beauty of RESTful interfaces and the HTTP spec.

Content negotiation is on the radar. Currently the negotiation is one-sided and depends on the request having a .json extension for example. This will be beefed up after the preview release.