Microsoft has upped the stakes in its battle with Adobe over development tools for rich internet applications (RIAs). 

The software giant released the first public beta versions of its Silverlight 1.0 RIA yesterday, allowing users to get their hands on the browser plug-in for the first time.

The move will allow developers formally to release applications built for Silverlight. A final release of Silverlight 1.0 is slated for later this summer.

Microsoft's announcement was made by chief software architect Ray Ozzie at the MIX07 convention in Las Vegas. Early alpha versions of the new Silverlight were also announced.

Silverlight 1.1 will support Microsoft's .Net framework, allowing developers to create RIAs with a number of different programming languages, such as Python or Visual Basic.

Silverlight 1.0 only uses JavaScript and Extensible Application Markup Language for development.

Users can run Silverlight applications by downloading a plug-in from Microsoft which works with Internet Explorer, Mozilla's Firefox and Apple's Safari.

Microsoft also announced a new component for Silverlight that will support streaming media.

Silverlight will compete for RIA developers with Adobe's Flash. Analysts have expressed doubts, however, that Silverlight will be able to make a significant dent in Flash's dominant position in the market any time soon.  

Microsoft has also rolled out a suite of web design tools dubbed Expression Studio, which includes programs for the illustration, layout and coding of websites.

The company also said that it would be opening its Windows Live services to outside developers. Microsoft introduced terms of service for developers wishing to add support for Windows Live Spaces, Contacts, and Messenger services.