It was an eventful period after beta 4. With excellent support from the community, we were able to identify and close quite a few trivial issues (and a few critical ones). The fifth 2.1 Beta distribution (probably last one before stable) is now available for download on SourceForge.
For all those eagerly waiting to being translation work on 2.1, we are now in "string freeze" - and the translation site has been updated with 2.1 files: http://translations.civicrm.org
If you are planning on using new 2.1 features AND / OR upgrading an existing site to 2.1 - NOW is the time to test the upgrade with YOUR DATA and identify any remaining issues with new or existing features. The development team will actively work with you resolve any upgrade issues during this phase of the release cycle.
If you are unable to test the release by downloading it - then the next best thing is to try out the new features, bug fixes, as well as the workflows you use most often by logging in to the public demo.