Doctrine 2.1 is feature complete and we packaged up the first release candidate to celebrate this day. So far we got exactly one backwards compability complaint that was immediately fixed. You only have about 10 days to verify that this release candidate is working with your existing 2.0 code-bases. If you find some problems please report a bug on Jira. We will provide everyone with mugs/tshirts who is finding incompatible changes.
We plan to release only 1-2 bugfix releases of the 2.0.x branch, which should give you lots of motivation to try out 2.1 with your projects.
We integrated a pretty substantial Annotation Reader refactoring just today. Please test if this still works with your code-base using annotations. See the UPGRADE_TO_2_1 file for some information. You might need to adjust your bootstrapping code to get it working.
The task now until the final release on june 30th will be to update the documentation with all the changes that have landed in Doctrine 2.1. We already created a 2.0.x branch of the docs that will freeze the current state for those staying on 2.0. Additionally we will squash all the last bugs that we find.
Grab the new code in the downloads section or on our PEAR channel