I'm not linking to a hacking site, not even in a PM because it's still moddable.
To Dragon Nexus, get your ass to Google, Halo 3 Title Update 3, search for it yourself, the update DOES exist, if you're really trying to claim it doesn't exist you're f***ing insane because it exists in 10 different languages.
Did just that. I find one and only one website that mentions it exists. No patch notes. No information on what's in it. No suggestion it's even legit. It might well be, but I'm not about to check it considering I've never heard of the website that shows up.
Every other source that shows up in Google lists 23rd September 2008 as the most recent title update for the game, which is likely to be title update 2, or at least the second downloadable patch for the game. It's entirely possible that is title update 3, with the first being on the disc already.
 to anyone who's curious... http://www.xbuc.net/browse/halo-3-english/ That's the site a user linked to me. I thought this was the purple text link that showed up in google, but that link was actually the Halo wiki again telling me about the two updates I already mentioned. Searching "Halo 3 title update 3" in google actually brings up nothing within the first 4 pages alluding to a third patch.