Mr. Chau.

This morning Betabeat learned that Rolling.fm co-founder and former Googler Tim Zhou had joined Tumblr. It has also come to light that another Rolling cofounder and Xoogler, Thomas Chau, has joined another prominent New York startup: Squarespace. "We liked Thomas's strong entrepreneurial spirit (take risks and run fast) along with his perfect Squarespace DNA of product design sensibility coupled with engineering awesomeness," Squarespace SVP Jesse Hertzberg wrote in an email. Squarespace, if you're not familiar, is a website builder and hosting platform (that is often likened to Tumblr, as it happens) founded in 2003. Now we just need to suss out what has become of the third Rolling co-founder, Xoogler Nhon Ma...

Mr. Zhou.

Wondering what happened to Turntable.fm's fast following, Xoogler-founded cousin, Rolling.fm? The social music site has been serving up errors for about two weeks; Tenka, the founders' previous startup, is also gone. Co-founder and chief product officer Tim Zhou, whose resume includes IBM and Google, did not respond to a request for comment by email, and now we know why.

It looks like Tumblr recently nabbed itself an Xoogler. Mr. Zhou created a Tumblr about one month ago and is now listed on the startup's staff page alongside 68 other employees (Tumblr, you're getting so big!)

We reached out to Mr. Zhou again this morning for comment. Our speculation? Rolling, a drastic pivot from deals provider Tenka, failed to raise money after being posted on AngelList (perhaps in part because no one wanted to compete against the golden child, Turntable).

Tumblr, meanwhile, is still hiring for eight open engineering positions as well as for Dutch and Swedish speaking ambassadors.

Indeed, Rolling.fm does not resolve and the last tweet was on November 19. Rolling's precursor, a social deals site called Tenka.com, is also not resolving.

The Facebook app had about 200 daily active users a month ago; now it has none, according to AppData. There's evidence that Rolling was active until at least Dec. 15, when the producer duo Dada Life premiered a remix there; Bnet interviewed the startup on Dec. 8.

Tim Zhou, Rolling's chief product officer, did not respond to an email request for comment. At present, the mysterious disappearance of Rolling.fm would appear to be due to three possible reasons:

1. Forgot to renew domain*
2. Cease and desist notice from scary record label
3. Failed to gain enough traction or funding, cofounders gave up on it (even Turntable's traffic has been slipping)

*A reader points out that the domain expires in 2012, so this explanation is unlikely.

Rolling.fm caught some flak from the internet when it launched in the wake of Turntable.fm's extreme success. The founders admitted they duped the idea, but appealed to the internet's tradition of innovation. (Even Steve Jobs subscribed to the doctrine of "good artists copy, great artists steal.")

The cofounders had pivoted from Tenka, a deals site that raised from seed investors including StubHub's Jeff Fluhr, Great Oaks Venture Capital's Ben Lin and Raj Sandhu, formerly of the Soros Fund. The site was available outside the U.S., unlike Turntable, which let them grab some easy users.

The cofounders switched to building Rolling in May, they said, which would mean Rolling had about a seven month run before giving up the ghost. But the co-founders put the startup on AngelList about nine months ago. We'll update as we learn more.