I'm sympathetic to both sides in the homeless dilemma but it does seem very mean spirited to take away the shopping carts from these people (re: article in TC today). I know it is theft and shopping carts are an eyesore still...
This photo is from the Homeless Vehicle Project which was featured in a book called "Portable Architecture - and Unpredictible Surroundings". This was a contribution from French architects and the idea was to have a distorting-mirror vehicle that could be driven by bicycle and used for living accommodation in the streets of Paris.
I thought it was quite neat although perhaps not completely practical as an alternative to shopping carts, but surely if we can put a man on the moon we could come up with something...