Geolocation in viewer? GPS Enabling?

[KarenEllett]

I've seen this post about using the network location information to show a user's location in the viewer:
http://davetimmins.wordpress.com/2011/09/20/geolocation-with-the-esri-silverlight-api/

This is clearly not intended for the OoTB silverlight viewer, however...  has anyone been able to create something like this for the viewer?  It looks like it would be possible to create a plug in that does something similar, but I'm afraid that it's over my head at this point.  Anyone?

Thanks!