Mike Arrington just confirmed the rumors: He's selling his five-year-old blog company TechCrunch to AOL. And he's sticking around for at least three years to keep running the site.

Arrington made his announcement on stage at his Disrupt conference in San Francisco, joined by AOL CEO Tim Armstrong. No financial terms were disclosed — we hear it was $30 million — but Arrington said TechCrunch's editorial freedom would be preserved under terms of the deal. As an example, the founder, editor and frequent TechCrunch contributor said that if TechCrunch obtained internal AOL documents from a hacker — the site famously came into posession of Twitter documents that way — he'd still expect to run the story. He added he expects to be able to continue to mouth off and make controversial statements in public.

Arrington, who recently moved to Seattle from TechCrunch's home base in Silicon Valley, said the deal also requires him to stick around for at least three years. That's just as well; it's easy to see AOL growing TechCrunch by giving it coverage areas now handled by other AOL sites. Daily Finance, for example, is said to be underperforming, and it's easy to imagine TechCrunch expanding its finance coverage further beyond Silicon Valley venture capital. If TechCrunch is to keep growing, and to simultaneously avoid losing its distinctive and often rambunctious voice in the maw of a big and comparatively ancient internet conglomerate, it will very much still need Arrington —who personally pens the site's most provocative scoops — not just around, but deeply engaged.

Update: Added initial deal valuation of $25 million to $40 million via Business Insider.

Update 2: A source close to AOL tells us the transaction was worth $30 million.

[Pic: Arrington moments after the announcement, via TechCrunch live stream.]