Update to AboutBox Extension
I recently posted an update the the WPF AboutBox (CS) extension (v 0.4) on the VS Gallery. You can find it by launching the Extension Manager in Visual Studio 2010 Beta 1. If you've already previously installed it, then click on the Updates tab on the left hand side of the dialog. This will query the Gallery for any updates to the extensions you already have installed. Notice that the WPF AboutBox (CS) should now appear there.
Also, you may notice that I recently posted a WPF AboutBox (VB) extension too. So now you can add this AboutBox to your VB apps too.