I have had an easier time with applications for the Mac then websites. There doesn't seem to be the website version of MacUpdate, rumor sites, or Apple Downloads. Maybe it is the difference between blog and community site.
How exactly would this work? The idea of doing a macupdate for web apps is somewhat intriguing, but with rolling updates, most web apps don't publish a version anywhere.
The delta is a lot less (webapps still add new features), but I think you would need to go the gdgt.com route and add a lot of search / categorization and community features.
