Fire starting with ice was done on Mythbusters. They also started a fire with a soda can and some chocolate - used the chocolate to polish the bottom of the can, used the can to concentrate sun rays on some tinder. Iirc, Dave Canterbury used a bag of urine to do the same.
All nice tricks, not gonna rely on them to start a fire in a situation.
I've seen it done at one of Mors Korchanski's classes. The sky wasn't even perfectly clear and even with the northern latitude of Edmonton, one of the instructors polished up a Coke can with chocolate and started up a tiny fire bundle. Then took the embers to a larger bird's nest and achieved fire. I didn't think he could do it in those conditions.
Since I am a Coke drinker and not a Pepsi one, I have heard it said that the curve on the bottom of a Coke can is a bit deeper and better shaped to do this. Just another reason to drink "the Real Thing"!