Various sources have suggested that the firm is readying Silverlight and its Expression Studio 3 suite of design tools for a 10 July release, although Microsoft would only say that an official launch would be "later this year".
The firm unveiled a beta of Silverlight 3 in March at its MIX09 developer conference in Las Vegas, showing off a number of additional supported media formats and new codecs, including HD content.
Other features expected in the new version include improved navigation, and the ability to work online or offline and even outside of the browser using Windows Presentation Foundation (WPF).
Further uses and development activity is encouraged through the release of a number of new APIs for Silverlight and improved support for graphics acceleration tools.
Despite Microsoft's refusal to confirm reports of a 10 July unveiling, copies of an apparent launch invite are appearing on the internet.
"See the light. Join us for the Launch of Silverlight 3 and Expression Studio 3 and see for yourself how Microsoft is helping teams light up Web experiences", the invite says, adding that it will be held Friday 10 July in the Bay Area of San Francisco.
