after install xcode 4.3 mysql.server start was shouting back at me and refusing to start:
ERROR! The server quit without updating PID file
installing the old, non llvm, gcc binaries and re-installing seemed calm the beast
brew remove mysql
brew cleanup
brew update
brew upgrade
brew install https://raw.github.com/Homebrew/homebrew-dupes/master/apple-gcc42.rb
brew install mysql
also, dont forget to follow the instructions after install
unset TMPDIR
mysql_install_db --verbose --user=`whoami` --basedir="$(brew --prefix mysql)" --datadir=/usr/local/var/mysql --tmpdir=/tmp