The update is available OTA at 112MB build number 11D5134c.
Apple has also posted Apple TV software beta 4 and Xcode 5.1 beta 4.
We are downloading the update now to see what we can find, but if you see anything, please let us know in the comments.
Update: No major changes in this beta, so we assume its mainly performance enhancements and bug fixes. The 'slide to unlock' text has been tweaked a bit to be a bit 'shinier' as well as the 'slide to power off' texts. Also, the Messages app no longer indicates "message failure" immediately after sending (thanks Yousefq25).