About 8 years ago the people that build the Maine Cat 30 cruising catamaran made a 22 foot model -- Maine Cat 22. It had a folding beam. It was pretty much a (dry) day sailor with a hard deck. I'll try to attach a pic. Here's a website with the specs.
http://www.boats.com/content/default_detail.jsp?contentid=7850

Other than the Shark, the Viva 27 from back in the mid-80s also had a folding beam. That was a pretty heavy duty design though.