Still learning how you guys want bugs reported. I was one of the new accounts that had the black screen issue. Just patched, got logged in, level 1 account.
Went into champ select, selected MF, realized I'd not set Masteries. Went into masteries, made a couple of selections, settled on +27 Health at level 18. Closed page.
Was prompted if I wanted to save Masteries. Selected Yes. Locked in champ, was last one to lock in. Game went to start, then crashed with the following report to Apple. In that Apple window, it asked if I wanted to Relaunch. I did, now I'm stuck with the game trying to: "Retrieving Data From Server".
Will try to kill it completely and relaunch.
Process: LoLLauncher 
Path: /Applications/LOL PBE/RADS/projects/lol_launcher/releases/0.0.0.64/deploy/LoLLauncher.app/Contents/MacOS/LoLLauncher
Version: 1.0 (1)
Code Type: X86 (Native)
Parent Process: UserKernel 
Date/Time: 2013-03-13 21:00:34.705 -0800
OS Version: Mac OS X 10.6.8 (10K549)
Report Version: 6