MySpace is sick, and its Slingshot Labs spinoff looks like the first appendage of the social network to be amputated. We're told Rupert Murdoch's social media lab is finally dead.

Slingshot laid off its entire staff and closed its doors just before the weekend, a tipster told us. The closure followed a series of defections and the cancellation of the labs' last big project, this person said. Slingshot was an incubator for MySpace technologies and was set up within News Corp. at the insistence of MySpace's then-CEO Chris DeWolfe. It has reportedly been in slow decline since DeWolfe was pushed out at News Corp. just over one year ago.

When we floated all-too-accurate rumors of Slingshot's impending doom back in January, Slingshot executive Diego Berdakin scoffed, telling TechCrunch our post contained unspecified "inaccuracies" and that "we have had tremendous success."

So much for that: Our tipster said Slingshot's would-be salvation project, a "LinkedIn killer" for the Wall Street Journal, will die with Slingshot. The "StreetFeed" site was supposed to be a sort of exclusive social network for job seekers and, had it taken off, might have saved Slingshot from death, as we reported previously. Apparently the product didn't inspire confidence within News Corp.

Slingshot was originally created as part of News Corp. Chairman Murdoch's efforts to retain DeWolfe (the pair are pictured together above, via Getty). It was 90 percent owned by News and 10 percent owned by the staff — part of an effort, no doubt, to encourage the long hours and dedication inspired by such equity in Silicon Valley.

But the equity lost its power to motivate after DeWolfe left: Amid evidence that News Corp. no longer supported Slingshot, our tipster said, co-president Colin Digiaro walked out the door, and is now at Mindjolt; he was followed by chief technical officer Travlin McCormack, now at; president Josh Berman; and Valleywag-trashing Berdakin, the VP of strategy, said to be pursuing a venture with Berman.

"Slingshot had been moving along quite well until the rug was pulled out from under it," said our tipster.

Slingshot had also been doing quite well for also-ran social network MySpace, developing technologies like SocialPlan, an invitation service "acquired" by MySpace and now used to send 4.3 million invitations per day. Who will save MySpace from the technically-savvy likes of Facebook now that its tech lab has been shut doewn? If you've got any idea, we'd love to hear from you.