Valve marketing man Doug Lombardi has clarified to Gamasutra the fate of Turtle Rock Studios - to an extent.
Bought by Valve last year, Turtle Rock was founded by former Counter-Strike bot developer Michael Booth in Irvine, California. It developed Left 4 Dead along with Valve, and was renamed Valve South.
"It's not like we shut it down," said Lombardi. "We bought the studio and we're still working with, I think, every single person from the studio."
After the completion of Left 4 Dead, some of the Valve South team - which apparently had only ever amounted to "nine or 11 people in total" - moved up to Valve's main office in Bellvue, Washington, to work on Left 4 Dead 2. This left so few people at the office, lombardi said, that "the idea of having an office and a receptionist... goes out of the window.
"That group of people looks like the original Turtle Rock again," he said, "and I think they may even prefer to call themselves that."
So: Valve South no longer exists; some of Turtle Rock is at Valve while the other lot are still working with Valve but might possibly be called Turtle Rock again. Glad we got that cleared up.