I just tried doing a fresh install from the nightly snapshot and I saw this warning repeated 7 times at the top of the install pages:

Warning: mb_convert_variables() [function.mb-convert-variables]: Unknown encoding "" in /home/.kalmuk/brendoman/brendoman.com/dev/180/inc/_misc/_misc.funcs.php on line 1083

The install seemed to go fine and the warning disappeared once the install process was over.

I'm using PHP 5.1.2.