I don't know about it being a motorcycle trailer, but they are pretty cool.
I've checked them out at RV shows. The little trunk in the back is often outfitted as a kitchen. They look quite comfortable as long as you don't need standing headroom and a bathroom/shower. Just about as economical as you can get.
Starting to see those Can Ams around my parts quite often. Wouldn't mind riding one once...I hear it's a totally different experience doing turns (no lean)...so initially they feel weird.
Love Rotax engines....PWCs and mini jets and snowmobiles. Having owned and ridding many SeaDoos myself (including a twin engine mini-jet...no boat could touch me 0-50!)