"Google has indeed bought ad technology start-up Invite Media," writes Peter Kafka of All Things Digital's Media Memo here, citing unnamed sources.

Updated: Founded in 2007 by a group of Penn undergraduates, Invite runs the Bid Manager web site for Web ad buyers.  Kafka estimated the deal price in the $70 million range. Google and Invite Media CEO Nat Turner aren't returning calls.

"People familiar with the transaction say Google's plan is to leave Invite running as a standalone unit, which will work at arm's length with exchange's like Google's AdX as well as competitors like OpenX, Yahoo's  Right Media and Microsoft's AdECN," Kafka adds. "Over time Google does plan on investing in Invite and integrating it with DoubleClick for Advertisers, its ad-serving technology."

Like a lot of Penn grads, Turner and his cofounders have mostly relocated to New York, to Invite Media's main office on 20th St. But there's still a group of Philly-based software engineers - including Penn, Cornell and Temple grads - based at Invite's office in a four-story apartment building near Rittenhouse Square, upstairs from the former Moon over Miami bar, now closed. Invite Media's receptionist there told me she's under orders not to buzz any strangers up: "People come here and try to poach our talent."

Invite's owners included Philadelphia investor Gil Beyda's Comcast-allied Genacast Ventures, and West Conshohocken-based Josh Kopelman's First Round Capital. Like Google, they're not returning calls.