You'll excuse me for not believing you...
If that is so why is it so drab, with a standard phBB format, and why does it have so few members? Furthermore, why is it that no other site regarding 343i references this one? Let alone 343i employee's twitters and profiles? (http://twitter.com/#!/ryanpayton etc. )
Aside from all these points of doubt - what do you have in way of verification of that claim? Aside from the title.
The forum appears to run by Twam and Bob, where the former is located in Toronto, Canada and the latter in Tallahassee, Florida. Since 343's quarters are in Redmond, Washington neither of these individuals can be staff at 343i.
I could go on, but I don't think it's necessary. As is standard, the burden of proof is on you guys to establish that this is indeed 343i's official site, rather than a fansite.
I hope you don't take this as offensive, as it was not intended to be.
Best regards,
-Mator
Edit: And don't even get me started on the site banner... made in paint? Yeah...