Google offers to host your application

Google App Engine is intended to allow the creation of scalable web applications by removing the need to worry about provisioning.
The Engine will provide automatic replication and load balancing as the number of users increases, as well as access to Google's APIs for services such as authentication and email.At this stage, Python is the only supported language, though Google officials indicated others will be added at a later date.
The Engine SDK includes an emulator that runs on a local computer so that programs can be tested before uploading to Google's systems.Applications running on the Engine can be made public or restricted to a specific audience such as employees of the company concerned.Several sample applications have already been created, including movie quotes, carpooling and chat.

The Google App Engine preview will be restricted to the first 10,000 developers to join the program, and each will be limited to three applications and 500M of storage plus other resources needed to deliver around 5 million page views per month.
Additional storage and bandwidth will be available for purchase "in the near future", according to Google officials. No indication of likely pricing was given. "Google has spent years developing infrastructure for scalable web applications," said Pete Koomen, a product manager at Google. "We've brought Gmail and Google search to hundreds of millions of people worldwide, and we've built out a powerful network of datacenters to support those applications. Today we're taking the first step in making this infrastructure available to all developers."