If it is a Cannondale. Maybe it's just a decal on a Micargi. I still cannot find a thing on such a beast anywhere, which leads me to believe it's mythical.
The headbadge doesnt' match what is publish for Cannondales. Cannondale aluminum welds have been smoothed (sanded). Post some detailed pictures of the headtube area and the rear dropouts.
That bike looks to be early 90's with the matching annodized compenents.
I think you nailed it Kingfish - it's a Craigslist ad, and he claimed not to know anything about it, wink wink. At least he's not claiming that it's a Cannondale, although he should explicitly state that it is not.