The speculation is over and today is the day Microsoft takes the developer covers off of Silverlight. There are a bunch of announcements today, so I'll break them down one by one, but for those in a hurry, here's the summary. First, Microsoft is announcing that the CLR will be a part of Silverlight (Channel 9 has a video with Scott Guthrie about this). Two, they are also announcing a Dynamic Language Runtime (DLR) which is open source and will allow developers to write dynamic languages to be compiled into .NET bytecode. The DLR will be open sourced under the Microsoft Public License. Third, Windows Live will provide Silverlight developers a way to deploy applications on their service by implementing a hosted solution around Windows Live.
The run down
Microsoft is giving out bits for two versions of Silverlight. The first is a beta of version 1.0. This includes Windows Media support and the other parts of the announcement that was made at NAB. Previous releases were all CTPs so for the beta the code is a bit cleaner and much closer to the final release. The second announcement is that the alpha version of Silverlight 1.1 is available. This release includes support for the CLR on the Mac and other developer related features that are going to make the RIA space much more interesting.
The cross-platform CLR
For me, the fact that Silverlight will contain the CLR is the most significant announcement today. It does a few things for Rich Internet Applications. First of all, it brings in .NET developers and gives them a way to deploy .NET applications on the Mac. That’s huge because the CLR is one of the best runtimes out there and being able to deploy full applications over the web will get a HUGE boost. The CLR is fast, efficient, widespread, and now it runs on the Mac as a web browser plugin while using XAML for the presentation layer. That means you can write C# and VB Rich Internet Applications that will run cross platform. All of this is great news and should result in a lot more developers looking at the RIA space.
Screenshots of Microsoft's Silverlight plugin and the applications that have been built on top of the runtime so far in the Silverlight gallery.
My collegue, Mary Jo had this nailed weeks before the official announcement. Microsoft is announcing and open sourcing a "Dynamic Language Runtime" w(DLR) hich will allow developers to write dynamic languages like Ruby or Python and have them compiled into .NET bytecode to run against the CLR so they get all the benefits. Because it’s open source, Microsoft is looking to grow the ecosystem by encouraging developers to implement other dynamic languages for the DLR. A lot of people seem very excited by this, and it *is* good news. That said, I'm not entirely sure how valuable it is. I'm not sure how many new developers it brings to the platform. It makes for a great story, and may make a difference in the long run, but it seems more newsy than beneficial at this point. Especially when you take into account the impact on the Silverlight download size (I hear it's about 400k).
Silverlight and Windows Live hosting (Silverlight Streaming)
Finally, one of the interesting announcements is that Microsoft is going to provide a hosting service to budding Silverlight developers via the Windows Live property called Silverlight Streaming. The serivce gives 4 gb of space to anyone building and deploying Sliverlight applications. This means you can store Slverlight movies and applications on the Windows Live service and then deploy those on your blog or web page. It's going to make it quick and easy to get started with Silverlight and give developers a free ride for storing some of their experiments.
All in all, Silverlight is great news for developers and means Microsoft has a "complete" offering when it comes to software. You can build desktop applications with Windows Presentation Foundation, build web-only applications with ASP.NET AJAX and now the hybrid Rich Internet Applications with Silverlight. Microsoft wouldn't give specific release dates for version 1.1, the version that has the most impact, but they said it would follow pretty closely after the 1.0 release.
Update: Thoughts are trickling in