In Dev10 Beta 1, which was just released, there isn’t any way to enable the Transparent Platform Extensions (aka Assembly Caching) or Out of Browser features for Silverlight 3 Beta. To enable these manually is pretty straight forward. However, you should note that they are currently incompatible with each other; you can use one or the other, but not both in the same Silverlight application.
To enable TPE, you need to edit the project file and add a new property:
Now, right-click the project again and choose Reload Project. Save the changes if prompted.
Enabling the Out of Browser feature is the same as in the Silverlight 3 Beta Tools for VS2008 SP1. You need to paste a chunk into the AppManifest.xml file used as a template when generating the AppManifest.xaml file. The file is located under the Properties node in Visual Studio:
To enable the OOB settings, paste the following snippet into the file (usually after the <Deployment.Parts> node):
ShortName="Your Out of Browser Silverlight Application"
Title="Window Title of Your Silverlight Application">
<ApplicationIdentity.Blurb>Description of your Silverlight application</ApplicationIdentity.Blurb>