Nope, they were officially rented from Apple at $999 for a maximum 18 month span. At the introduction of the Intel iMac, the developer got a free iMac Core Duo when they sent their Transition Kit back. The DTKs were *NOT* purchased. They were *REQUIRED* to be returned by December 31, 2006. (Although Apple didn't exactly make a huge effort to get them back.) The iMac became theirs to keep, though; which obviously prompted most developers to trade in. (Not to mention the Core Duo was a *MUCH* better chip, other than lacking 64-bit support.)
My Intel friend says it is a "Barracuda" board. (As you could probably tell from your photos.) And other than the basics of what's on the board, that I've already told you, not much more info is available from Intel. It was just another OEM-specific prototype based on a production board to them. On Intel's internal part lookup site, there wasn't even any mention that it was for Apple. (I didn't tell him exactly what the board was, I just gave him the part number and serial number. He could tell the basic stats, and that it was a prototype not for sale.)