One of the problems with Amazon EC2 was the dynamic nature of the IP address that you received for each instance you started up.  For development it isn’t a big problem, but for a production system you can see the problems this can cause if you instance fails for some reason.  This morning Amazon announced the ability to have a static IP that is associated with your AWS account.  By default a user can have up to 5 static IP addresses.  The IP addresses are free of charge as long as the IP address is associated with a running instance.  If the IP isn’t then there is a charge of $.01/hr.  You can read more about this on the Amazon Web Services Developer site.