Also like a plus for the people how don’t already own it can buy it at half price, so if you don’t have Gmod why not buy it now?
It comes with SteamPlay so there is no need to buy it again if you already have it on Windows, also people using mac will be able to play together with Windows players, and all the same stuff that comes along with the Valve Mac Releases.
The only thing different is that you need a Source engine game to be able to play Gmod, making it one the first available Source mods for Mac.
As for mayor changes there have been some updates for the menu like the merge of Single Player’s and Multiplayer’s create game dialogs, and some progress on the Cloud System(a.k.a. Toybox) like the inclusion of maps upload and download content.
More here: http://www.garrysmod.com/2010/09/23/gmac-today/
…and here: http://www.garrysmod.com/2010/09/24/garrys-mod-for-mac-is-out-50-off/
By the way I’m Iñaki one of the LambdaGeneration staff guys and this is my first post.