I hadn't heard of it before the announcement, but MacTech magazine says that their MacForge.net site now is hosting more than 50,000 open source projects. Now, before you say "Wow! That's a lot of Mac programming! Why isn't Apple crowing about this?", you need to know what to expect. These aren't all Carbon and Cocoa apps, lots (probably most) are apps that involve other technologies that aren't Mac-specific, like PHP, X Windows. There is a toggle somewhere in the user preferences for the site that will "limit the view to those explicitly on the Mac." Even with all the non-Mac-specific stuff it seems like a great resource.