Serial entrepreneur Martin Tobias finally unloaded his swish south Queen Anne house, selling it for $4.3 million to a Florida biotech executive.

Tobias worked at Microsoft before starting Loudeye Technologies, joining Ignition Partners and leading biofuel venture Imperium Renewables until just before it scuttled its IPO.

Most recently, Tobias started a Web site called Kashless where people can list free stuff they're trying to get rid of, a bit like the free listings service on Craigslist.

Along the way Tobias built a modern house on West Prospect Street, not far from Queen Anne's Kerry Park viewpoint.

The four bedroom, 3.5 bath house, featured in this Pacific Northwest magazine spread, included 10-foot-tall glass doors and an acrylic staircase. Here's a pic by our Benjamin Benschneider:

Last summer the place was listed for $5.9 million, but sat on the market through the economic downturn. King County values it at $2.65 million.

King County records show that Tobias sold the house a week ago to Brent Stiefel.

It turns out he's the same Brent Stiefel whose family sold its Florida-based dermatology drug company to GlaxoSmithKline for $3.6 billion in April.