Secondly, Logitech MX Revolution mouse users and MySQL users note this...
Apple has moved Expose and Spaces into the Utilities folder, this breaks the Expose and Spaces button mapping for the MX Revolution mouse. To fix this, copy (NOT MOVE) Expose and Spaces into the Applications folder, things will be fine until Logitech releases a new version of their software.
Apple also moved MySQL, you'll need to create an alias to fix this until a new version of MySQL is released.
sudo ln -s /usr/local/mysql-5.1.37-osx10.5-x86/ /usr/local/mysql