A Steam client update is now available. To apply the update, click the File menu inside of Steam and then select "Check for Steam Client Updates...". The specific changes include:
Steam Client
Reduces bandwidth used for stats and achievements on OSX
Improves reliability when multiple achievements are unlocked simultaneously
Fix for possible Steam lockup when launching a game
Added 'view game store page' option on the context menu for friends who are in a gameFixed steamclient.dll importing a function not available on Win2k