Sources tell Valleywag that AOL is the middle of closing a deal to buy social media success story Mashable, the world's largest tech blog. Someone inside AOL slipped Valleywag's Ryan Tate the scoop and Robert Scoble seconded the rumor.

We first told you about Mashable founder Pete Cashmore last October when we nominated him as one of our 30 Under 30 honorees. At the time, Mashable was getting 7.8 million unique visitors and 12 million pageviews a month. Its snappy, digestable how-to posts on leveraging Twitter for your small business, or which 5 iPhone apps you can use to boost productivity helped pique interest from mainstream audiences new to the social media landscape and trying to navigate it to their advantage.

That practical, consumer-oriented appeal helped Mashable overtake Techcrunch's more insider-y approach to tech news last June. Cashmore told me, "It's just always been very much our DNA to give a view of technology that is processed and digested for a more mainstream audience. We don't necessarily see ourselves as a a tech industry pub, we see ourselves more as a consumer publication, more in the frame of a Wired than a computer industry insider publication."

According to Tate, his source inside AOL claims, "it has not escaped AOL's notice that Mashable writes the sort of content advertisers pay for at a time when AOL's own editorial staff has been heavily reduced amid company layoffs."

Adds Tate,

A deal would work for AOL, newly spun off from Time Warner, as well. CEO Tim Armstrong wants a "laser focus" for the company, on content. He's already bought a local content company from himself and launched a strategy to tailor content to internet statistics like search queries. . . The only hitch might be negotiating with AOL; visa issues have had Cashmore hopping back and forth between Silicon Valley, where Mashable is based, and Scotland, leaving one Valley observer to wonder if he would really attempt negotiating with AOL "from his parent's basement in Aberdeen."

When I spoke to Cashmore in September, he was actually spending the majority of his time in the U.K. after living in San Francisco's Nob Hill for most of 2008. "I find I get a bit more balance that way if I'm away from it and take a long view," he said. "It's somewhat advantageous to be able to look at this from a distance." In his Nob Hill days, Cashmore was a frequent visitor at the offices of Web 2.0 darlings like Bebo, which AOL purchased for $850 million in 2008.

As Mashable's focus has evolved from serving the the niche to the masses, Cashmore said his attention has likewise turned to Mashable's growing East Coast hub. "Right now we're kind of more focused on New York City," said Cashmore. "We're seeing this transition of mainstream media being more social and being online. So that's been more of a help for us than the West Coast this year. We've got our COO there, our managing editor, our editor-in-chief is moving there."

Valleywag credits Inc. with popularizing Cashmore as "the Brad Pitt of the Blogosphere." But we were merely quoting from this (slightly tipsy, maybe flirtatious) interview Cashmore did back in the day with Vino Diaries' Sandra Ponce de Leon.

No word yet from Cashmore on whether the AOL rumors are true. UPDATE: Cashmore weighed in on Tumblr. "We've certainly spoken to lots of potential partners, some of those conversations more significant than others. But I don't feel that any of those conversations reached a point at which Mashable is likely to cease being independent in the near term."