Silverlight 4 to launch April 13

Microsoft execs said last month that the final version of Silverlight 4 would be available in April. It looks like the "launch" date is April 13, though as of April 7, company execs weren't ready to promise that's when final code will be available.

An aside: In Microsoft's world, "launches" are not necessarily simultaneous with "release to manufacturing" and/or "release to the Web." Sometimes launches follow RTM (as will be the case with Office 2010) and sometimes they precede the RTM/RTW.

I'm betting Silverlight 4 will be released to the Web on or before April 13, and I bet Microsoft is, too. But a spokeswoman would only say: "April 13 is the launch, but we haven’t announced a specific date for the release. Silverlight 4 will be available later this month.")

Update: Microsoft officials said on April 13 that the final Silverlight 4 bits won't be out until April 15. I lost my bet ...

It's going to be a busy one for Microsoft's developer division next week, with Visual Studio 2010 launching on April 12. (VS 2010 also still has yet to be released to manufacturing, as of this writing, but I'm guessing it will by Monday next week.)

If you are interested in watching the Silverlight 4 launch -- and Corporate Vice President Scott Guthrie's keynote -- via Webcast, it starts at 11 a.m. ET.

Given that Silverlight is now the primary development environment for Microsoft's Windows Phone 7 platform, wannabe Microsoft Phone developers may want to tune in to see what's coming for the platform, even though Microsoft will be running a hybrid of Silverlight 3/4 as its first-generation Windows Phone 7 dev environment. Silverlight 4 won't run on the Windows Phone 7 devices right off the bat, but Silverlight will be supported on those phones (someday)....

Softie Tim Heuer has a blog post with a detailed list of the features are in Silverlight 4 (as of the Release Candidate, which Microsoft delivered last month).