Amazon, today expanded their EC2 offering to include db's in the cloud. This will extend it's native database application: EC2 SimpleDB. The two new options are Oracle and Mysql. This further reduces the "barrier to deployment" of applications on AWS.
One of the main problems firms had when trying to decide upon AWS, was the portability of their application once built using Amazon's proprietary services. Hopefully now, it should become that much easier to move your database at least unto this service. How the complexities regarding Oracle licence's and keys is yet to be seen, but it seem's they are working closely with Oracle so that might not be as much of a problem.
Welcome to enterprise in the cloud!!!