The code is in it's own repo at : http://github.com/callback/callback-windows-phone 

• fork/git or download/unzip the repo to your harddrive 
• copy the file GapAppStarter.zip to the folder
•  \My Documents\Visual Studio 2010\Templates\ProjectTemplates\
• Launch Visual Studio 2010 and select to create a new project 
• PhoneGapAppStarter should be listed as an option, give it a name
• Right-Click on the solution and select Add->Existing Project, and add the project  framework\WP7GapClassLib.csproj from the downloaded repo
• Right-Click your main project and "Add Reference" to the WP7GapClassLib project

• build and run!

More details to come. jm