Also if you're running OSX 10.6 (Snow Leopard) or 10.7 (Lion) there isn't really any reason to update to this version. It's the same build as v2.5 aside from the Mountain Lion support.

Also the Sep-1 v3 beta released just a few days ago also supports Mountain Lion as well. Version 2.51 is just an update for the previous 2.5 full (non-beta) version to also support Mountain Lion.

- Michael