No details of what is new in the Beta have been released but Apple is expected to be wrapping up development of the beta to coincide with a late-June release.
On a more quiet note Apple gave a select group of developers access to the latest iPhone OS 2.0 build, build 5A308 comes on the heels of a build last week that added the addition of geo-tagging.
The latest build is said to speed up the iPhone OS significantly.