The next version of Silverlight isn't just a browser plug-in to do Flash-style video and interfaces; in fact (as with Adobe's AIR) you don't even need to have your browser running to use it, so Silverlight 3 Web applications can run in their own window and have their own desktop shortcuts.

You can even pin them to the taskbar in Windows 7 .You don't have to be online to use them either; depending on how Silverlight apps are written you can carry on using them without a connection and changes you make offline can be synced when you connect again.

And it all works on Mac as well as Windows (and in Firefox as well as IE).

Don't some apps need to be online?

Some features can never work when you're not on the Internet, like streaming Internet radio; but Seattle radio station KEXP showed its streaming Silverlight player at the Las Vegas MIX conference where Microsoft announced Silverlight 3. It lets you leave messages about the track that's playing when you're online and offers to play monitors and videos you've already downloaded from the station when you disconnect.

Silverlight still majors on video features, but there are lots of video codecs, not just Microsoft's VC1 HD codec (used by both Silverlight and Blu-Ray). Silverlight 3 adds more, including MPEG-4, H.264 and AAC. NBC will be using Silverlight for their 2010 Winter Olympic coverage, in true HD video.

There are also plenty of other media features, including smooth variable-bandwidth streaming and PVR controls for pausing live video and watching clips in show motion, broadcasters need to use Microsoft tools to stream media.

GPU time

Microsoft is offloading a lot of Silverlight's video effects grunt work to the GPU. The latest graphics cards mean Silverlight 3 will produce video effects in real time. Effects aren't just for video – you'll see special effects on forms and text.

Corporate Vice President Scott Guthrie calls it "upping the ante on graphics on the Web". However, as Flash has proved in the past, it's too easy to use these effects gratuitously, and he begged his Mix audience of designers to "use these powers for good, not evil!"

Rich Internet Applications running in earlier versions of Silverlight are hard to search, hard to bookmark, and hard to share. Silverlight 3 adds features for search engine optimisation, generating real URLs for different parts of an application. What's good for Google is good for you, as you'll be able to deep-link into Silverlight applications – just copy and paste the URL. The same techniques also mean it's easier to track just what goes on inside a Silverlight application – the downside is more and better targeted adverts.

Microsoft claims over 350 million installations of Silverlight but Flash is on virtually every PC in the world. Developers like Silverlight because they can write in familiar programming languages, but Guthrie points out other advantages; if you have a multi-touch screen, Silverlight supports multi-touch gestures. "Deep zoom, multi-touch – those are things Flash doesn't have."

Deep zoom is one of the reasons Rolling Stone is going to use Silverlight to make 40 years of back issues available online; www.covertocover.com will go live this summer – and in the meantime you can browse 54 free issues of Playboy!

Smaller download

The new version of Silverlight is actually 40K smaller than Silverlight 2; the download is 4.4MB which takes less than 8 seconds to install on the average broadband connection. That's not counting the size of applications or the controls they use, but applications can now share controls so you don't have to download them twice.

And both applications and controls can get updates automatically the next time you run them; Kevin McEntee, the vice president of Web engineering at Netflix says they picked Silverlight because it lets them stream video on the Mac but found updates so easy they're trying out tweaks to their streaming algorithm every two weeks.

Silverlight 3 is available in beta now; like Windows 7, there will only be one beta version and the final release will be 'later this year' (possibly at the Professional Developer Conference this autumn).

Don't hold your breath for a mobile version of Silverlight; although Scott Guthrie promises Microsoft is "still on track" he won't say whether it will come out in time to have Silverlight 2 features or whether it will take long enough to be in sync with Silverlight 3 (and so there won't be a public beta for it).

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