The cloud computing model gained further validation after IBM announced that it is now delivering some of its infrastructure software as an on-demand service through Amazon Web Services.

Customers will be able to use the IBM software on a pay-as-you-go basis for both development and production use via the Amazon Elastic Compute Cloud (Amazon EC2).

The software includes instances of IBM's DB2, Informix Dynamic Server, WebSphere Portal and Lotus Web Content Management. This will be extended over time to include IBM's Tivoli management software to help clients better manage cloud infrastructures, IBM said.

The pay-as-you-go services will be available in the coming months, and pricing for those has not yet been released. However, IBM said customers may be able to transfer existing IBM licenses to EC2 immediately. More details are at the Amazon Web Services website.

EC2 is a web service that allows customers to buy compute capacity on an as-needed basis. The model allows them to avoid up-front equipment costs and scale their capacity up and down as demand fluctuates.

This is IBM's second cloud-related announcement this week. Earlier this week, IBM and Juniper demonstrated technology that will allow companies to shift workloads between private and public clouds - or between their own data centres and a service like EC2.