[delano]

EC2 charges only for the time you use, rounded to the next hour. A small instance running for 6.1 hours costs $0.70 + bandwidth.

http://www.amazon.com/FAQ-EC2-AWS/b?ie=UTF8&node=2015910...

[briansmith]

My understanding is that EC2 charges for wall clock time. I heard a rumor that Google was going to charge only for the actual CPU time used. In other words, if your service is totally idle, Google will be free but EC2 will cost you $84 a month per server.