Kudos to Mantra for pointing out this forum post made by Bungie's Matt Soell at HBO. In a predicatable turn of events, he debunks the confirmation of a PC version (and the absence of Mac confirmation):

Sounds like one of three things: a Microsoft PR flack who didn't know what he/she was on about, a PC Format staffer who misinterpreted what was said, or a little bit of both. If I had to pick I'd probably go with Door #3.

No decision yet means exactly that. We don't know yet and neither do they.

More to be said in the forum post, but I think this is a helpful reminder that, if Bungie hasn't announced it, it's probably not 100% reliable. Especially something like this.