Happened to come across a photograph in the newspaper the other day- on the anniversary of the Tsunami, I think- of people releasing luminaria (lanterns) that seemed to float in the air!- does anyone know how to make those?

Albuquerque Tricentennial

They don't float in the air though.. :p

Could they work like hot air balloons? Maybe they work with a little tea light instead of a heavy gas motor engine thing.. ;)

Here's a website on how hot air balloons work if you need.