Update: Whiple, responding to the reports, says his tweet "wasn't meant to be an announcement" and notes, "We're still exploring a console version, but more importantly working on the PC/Mac version."
As of February, Blizzard was "looking into" a console version of Diablo III. Now, community manager Micah Whiple aka "Bashiok" has confirmed via Twitter the project in fact does exist, though if it's in development for both PS3 and 360 we can't say.
Whiple also notes designer Josh Mosqueira -- who previously worked at Warhammer developer Relic Entertainment -- is leading the project. Doing a bit of digging, we see Josh is himself on Twitter and just last week posted a job listing for experienced console designers to work on Diablo III. The company had previously put out searches for console work, though, so how far along the project is is tough to say.