From your beta page you can get 4.9.30.
This version mainly attemps to fix race conditions while switching between UP and leave state (like having 3 UPs as a leaf and some leaves...)
This version also waits you get some uptime before promoting you to UP at LW startup. This is done to increase the network density because there are too much UPs right now.
LW also tries using random port if it is always firewalled on port 6346.
Many languages were also updated.
Well those were the "unofficial" release notes from what I saw in CVS....
Maybe the official will be available tomorrow.
Ciao