Here's a list of the most noteworthy things in the RAP 2.1 RC2 release candidate which is available for download since May 31, 2013.
This list shows all bugs that have been fixed for this release candidate.
The above features are just the ones that are new since the last milestone build. Summaries for earlier builds:
After 6+ years of development in the 1.x stream, we're cleaned up some API in RAP 2.0. To assist you with the migration from 1.x to 2.0, we maintain a migration guide.