The beta release follows a preview version done in May, said the developer, who has shepherded the project at Novell.

"This means that is now feature-complete and we consider it ready to test against Silverlight 2.0 sites. Users who have installed Moonlight 2.0 previously will be offered a chance next time they start Firefox to upgrade to the beta," de Icaza said.

Moonlight trails Microsoft's Silverlight 3 in functionality, he said. The API implemented by Moonlight 2.0 is a super-set of Microsoft Silverlight 2.0.

"Although Microsoft has already released Silverlight 3.0 with new functionality and APIs, it will take some time to be fully adopted, so while we might be behind Microsoft's offering, we still think that this will allow users to access most Silverlight content out there today," de Icaza said.