the long tail cargo bike is an amazing platform
yes, I've done some touring with on a Cannondale XtraCycle convert
at the moment I'm using a Surly Big Dummy which I've had for over 2 years.

here's a couple of links:
http://forums.mtbr.com/showthread.php?t=519016
http://forums.mtbr.com/showthread.php?t=391518

at the moment a buddy and I are here in Monterey, getting ready to finish up our trip Eureka, Ca and south.

we just finished going thru the Lost Coast, Kings Range and Sinkyone Wilderness... about 125 miles of dirt, then a bunch of pave from Ft. Bragg, Ca and south.