I’m at Microsoft’s Mix 09 conference in Las Vegas, where VP Scott Guthrie has unveiled Silverlight 3.0, the next iteration of the cross-platform browser plugin that renders multimedia and executes .NET code.

There’s plenty of good stuff in Silverlight 3.0 and it’s been well received. Highlights are pixel-level graphics API (which lifts any restrictions over what kind of user interface you can do in Silverlight), offline/desktop app support, deep linking which means you can have urls that point to dynamic pages within your applet, binary XML for fast access to remote data, ClearType fonts, import from Adobe PhotoShop and Illustrator, lots of cool features in Expression Blend 3.0 (which now looks like a tool that designers might actually want to use), and support for more media codecs including H.264 and AAC.

Can Microsoft beat or match Adobe? One notable aspect of Mix is that the people here seem to be largely Microsoft platform developers (not designers), interested in rich internet applications and going cross-platform. The sessions here on developing business database applications have been packed.

It is a contrast to the attendance I saw at Adobe’s Max Europe, which was designer-focused with Macs everywhere. There’s little evidence so far of Silverlight breaking out of the Microsoft niche (large though that is) and becoming something that the wider web development community takes seriously.

That could change if Silverlight achieves greater visibility and installed base (latest figures from riastats show only around 20% of browsers have the plug-in installed). The Soyatec Eclipse-based development environment, which apparently Microsoft funded, could also be important, since many web developers and designers do not run Windows.

Still, I don’t want to underplay the significance of Silverlight within the Microsoft community. The guy from Netflix made a big point of the value of zero install for Silverlight applications (once the runtime is installed). Many users are wary of anything that has to be installed, whether through fear of malware or simply experience of bad installs. Add cross-platform to that, now with desktop support, and Silverlight looks attractive for .NET developers.

Mono leader Miguel de Icaza made an interesting comment on Twitter today:

Wpf will be irrelevant because sl3 is xplat and the subset that matters. Full machine access is irrelevant or trivial to do

I also spoke to Microsoft Rich Client product manager Brad Becker today, who told me that one day WPF and Silverlight might merge, or become different profiles of the same thing.

Silverlight is becoming capable enough that it could be used for an increasing proportion of business applications. It fits the cloud computing model, and if this grows as expected then being sandboxed from local resources becomes less important, and of course has security advantages.