Spokespersons for Microsoft and all other sources on the subject are remaining mum today, after an unofficial general release deadline of the end of November for the next edition of its Silverlight Web apps platform passed quietly. The Silverlight 5 project had been launched as the evolution of Microsoft's graphical platform for Web functionality, though that was before the company's dramatic shift in preference to WinRT as the Web apps platform of choice for Windows 8.

Late yesterday, Microsoft's spokespersons were unable even to confirm that Silverlight 5, whose release candidate remains available now, will make general release in 2011. However, a launch announcement page posted earlier in the year continues to show 2011 as the promised timeframe. One spokesperson would only say that further news would be revealed "in the coming weeks."

The November timeframe came about as a result of a statement attributed to Microsoft Corporate VP Scott Guthrie, who remains recognized in the Microsoft developer community as a champion of the platform. However, that attribution failed to take into account that Guthrie had already moved to the Server and Tools division which is not accountable for Silverlight. (Guthrie replaced Bob Muglia who left for Juniper Networks.) So Guthrie perhaps should not have been treated as the final word on the subject; had the news come from S. Somasegar, it might have carried some weight.

During an RWW interview with Microsoft executives in September, Somasegar - the current CVP of the Developer division - was clear and unambiguous in revealing that the Silverlight effort is being scaled down. So that's not at issue; what does concern developers at this point is how they should plan to implement their own skillset transitions from Silverlight to WinRT.

What Microsoft told us would survive during this transition phase is XAML, the resource description language critical to Silverlight. XAML uses XML-style markup to denote the locations of page elements and controls, and as some developers would argue, is much better suited to the UI of a complex application than HTML. At last September's Build conference in Anaheim, company representatives demonstrated XAML in developing next-generation apps for Windows 8 outside of Silverlight.

But while the structure of XAML may survive the transition, testers of WinRT are finding out that the various controls and elements that XAML would normally reference in Silverlight have yet to make the journey. On the company's development forums, registered partners are already compiling lists of thus-far-unsupported features in WinRT.

"I appreciate that WinRT is still in developer preview phase and it will change by the time Windows 8 beta is released," writes forum member Sameer V. "But the suspense and secrecy is killing me! First we were worrying if XAML will be present in Win8, now that it is there, it's almost unusable (at least for my app)... I hope someone from MSFT is listening, we need some transparency guys."