Yeah, I mean as long as you don't post in rumor threads you should be fine. I bet that Apple has employes that spend the day combing these type of sites, so see there are Apple employes posting on rumor sites. Come out and reveal yourselves!
Don
A lot of Apple employees read & post to these sites, no doubt.
I doubt if many of these instances are "flagged" by Apple, but if there was an information leak they certainly would have a history of all external comms, though there are ways around that..
They're not going to fire anyone simply for browsing/participating in this site, but if your project was leaked to the public and your history shows you frequent rumour sites, it's a handy clause for them to have in the contract which means they can easily terminate you without having to prove you leaked the info.