Bentech Recumbent Bike Plans - Plans "blueprints" if you will are available for two models a SWB and a LWB.

CruzBike - Update 2006:  I don't know much about these, but they seem to be doing pretty well and definitely worth checking out for those of you're without the huge budget some manufacturers demand.

This is essentially a conversion kit to change a standard mountain bike frame into a recumbent type bicycle.  Who knows how well this will work, it looks like an odd geometry to me with the rider further forward than usual.  Will this effect braking and handling?  Is this a recipe for emergency room visits?  Reminds me of the engineering project I saw on Public TV where a guy has been working 20 years to make a plane that flies by flapping it's wings.  I guess time (and a few experienced riders trying the thing out) will tell.  I doubt riding 10mph on flat terrain would be much of a problem, but who does that? 

Steve's Recumbent Bicycle Project - Listed here instead of on the personal sites because of the construction ideas and plans presented.  Plus some excellent photographs of the bikes and process as he has built them.

Bicycle Plans