Mac Lion Mountain OS X 10.8.2
$ brew install wget
$ install mysql
if it gives error manually download the file to brew cache folder
$ wget https://downloads.sf.net/project/machomebrew/Bottles/mysql-5.5.28.mountainlion.bottle.tar.gz /Library/Caches/Homebrew/
then runt he mysql install again it will load the file from cache folder.
$ brew install mysql