Burton, actually the tail of a streamliner is very important. The reason most streamliners have such long, gently tapered tails is because that's the only way to keep the flow laminar all the way to the back of the vehicle. It's a major pain in terms of making the bike longer, more difficult to maneuver and such, and some would say it's not very aesthetically pleasing too, but it does yield a lot of efficiency gains.
Mike Corbin has a very interesting approach on his new Swallow II (I think that's what he calls it). He's chopped the end of the vehicle off flat, making for a much more compact and conventional look, but he's added dimples maybe 3" in diameter on the back half, hoping to improve on tail-end aerodynamics the same way dimples do on a golf ball. I think it has a lot of potential -- even the Mythbusters tested it and found that it works, on a regular (not very efficient) car. I'm eager to see how it works out.