In the new Star Wars Insider's ask Lobot section someone asks the question that has plagged Star Wars fans since 1980.

Why is Lando wearing Han's clothes at the end of Empire?

The explanation they give is that Lando didn't have time to pack when he left Cloud City so is borowing Han's clothes whyst he's trapped in carbonite!

I still prefer my explanation though. They where origonally Lando's clothes but he lost them in the same Sabacc game that Han won the Falcon in. Lando didn't have enough credits so Han took everything including his ship and the clothes off his back. Lando walked away from the Sabacc table completly bolluck naked!