This is a rather speculative news story, because I'm not all that certain that there's any news here at all. However, I figured it's better to report and retract than not to report at all.
As most of you will know, the TF2 Mann vs. Machine update was released today/last night. Understandably, the Left 4 Dead blog updated with the news, telling players that they could go and enjoy a similar style of gameplay over at TF2. However, in the news post, they made a typo in the link to the TF2 bog post, so that rather than reading "http://www.teamfortress.com/mvm/" (which it actually directs you to if you click), it reads "www.teamf6rtress.com/mvm/".
No big deal, one might think. A simple typo. However, if you copy the link into the browser and visit the typo address, it takes you to this page. A fairly well-faked copy of someone's Steam Community page. Looking at the top right, it claims that the user is playing "Half-Life 3: Indev", with a link that redirects to the real steam store. However, the link itself ("http://store.steampowered.com/app/1273550") is unique enough to raise some eyebrows.
By going back to the main site that was hosting the fake Community page, I visited the owner's twitter, where 7 hours ago he sent this tweet:
@PhantomTheft Hey, 1273550, Monday.
Obviously, that's the same number as was in the supposed steam store HL3 link. The tweet was sent to a twitter account that had been inactive for the past two months, until today's tweet. He replied "@cmcmanning Ever. Of All time."
So what we have here is quite confusing to say the least. If it didn't start at the official Left 4 Dead blog, one would quite easily discount everything. However, it does lend a certain air of authenticity to what otherwise looks like a joke.
One possibility is that the typo was made accidentally, and the user that saw it quickly registered the domain and had it redirect to his site, where everything else was his doing. It seems unlikely that this is anything more than a fairly elaborate troll, either on Valve's or this individuals's end, but I thought it better to write it down. Is that news? I don't really know.
[Update the 1st] According to the Steam Forums, the domain was bought hours before the L4D blog post, which rather eliminates the possibility of an opportunistic troll. Though of course time zone confusion could explain this.
[Update the 2nd] A recent comment on the real profile page for 'Chase' indicates that my first thought may well be correct. "Best 10 bucks spent. Ever." was left an hour ago by PhantomBot, the owner of the previously mentioned Twitter account, obviously referencing the cost of purchasing teamf6rtress.com.