Yuba Mundo / Bikes-at-Work custom hitch detail
Here's a detailed shot of my custom hitch that attaches a Bikes-at-Work trailer with a Yuba Mundo v3. It has the ability to rotate to some degree in every direction.
So far, it has worked very well, although there not a lot of clearance between the pin and the frame at some angles.
For a competing hitch design for this trailer and bike, see the Rock the Bike Mundo/Bikes-at-Work hitch Their design includes a longer arm further towards the back of the bike. Their design offers a superior range of motion, while Kurt's design shown here has the benefit of being set closer to the rear axle, reducing the chance that weight on the front of the trailer will cause the front of the bike to come off the ground.
Frankly, having used one design just a little and not having used the other, I can't say which approach is best. Rock the Bike has been combining this bike and trailer for longer, and may include some design elements learned from experience.
UPDATE 10/17/2010: this hitch placement turned out not to have enough clearance when combined with the running board accessory. I'm testing an updated design now, which follows the same pattern above, but moves the hitch further back . This closely matches the placement of the Rock-the-Bike approach, including a bit of a downward slant, to match the angle that the trailer arm approaches the bike.