Microsoft officials wouldn’t say a month ago whether the actual Silverlight 3 bits would be available by the day of the official launch, which is July 10. But it turns out they are available a day earlier.
If you try to install this version but you have already Silverlight 2.0 for Developer installed on your machine, you will get error message: Unable to install Silverlight. Your Silverlight developer components are out of date.
If you are not a developer and want to avoid this error, please uninstall previous Silverlight version first by following the Silverlight Uninstall Instructions. If you are a developer, download and install Silverlight 3.0 for Developer here.
Installation will upgrade current version of Silverlight on your machine. You do not need to install Silverlight 3.0 if you have installed Silverlight 3.0 for developer.
Same as previous version, Silverlight shipped not followed with developer tools. Expression Blend 3 and Silverlight Tools for Visual studio still Beta or RC. Expression Blend 3 + SketchFlow RC available for download from http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=92e1db7a-5d36-449b-8c6b-d25f078f3609. I'm still waiting for RTM version of developer tools.