As Matt mentioned, we have begun 2.2 development. We’ve already committed some nice new things including Atom API support, WP-specific XML-RPC API for managing pages and categories, and TinyMCE 2.0.9. We’re also fixing bugs in 2.1 and 2.0.7. Once we shake out enough bugs, we will package 2.1.1 and 2.0.8 releases. You can check the roadmap to see what bugs are being fixed for each release.
If you’re using subversion to grab the latest updates, note that 2.2 development is happening in trunk, 2.1.1 development is happening in the 2.1 branch, and 2.0.8 development is happening in the 2.0 branch.