BIRT 2.6.2 has been released. The 2.6.2 is the second bugfix release for 2.6. If you want to know what has been fixed in detail you can have a look at the projects bugzilla. The most fixes are chart related.
The next BIRT release will be a major release and is planned for June 2011 with a bunch of new features (OpenOffice support, simplification of runtime deployment)
In addition the actuate guys updated their BIRT book “BIRT – A field guide to reporting“.