I think part of the success of this website is that apple legal won't touch it, because this site doesn't post any leaks from its own sources, instead it just rounds up the rumors from all the other rumor sites.
The other part, (the major part) is the fact that this place is the BEST Apple website period. Even apple.com pales in comparison to the amount of information and help you can find on this website.
And finally, the fact that since this is a mac community, everyone is awesome.