Hi, I am working this summer on the project "Communicating with mobile devices" for the GSoC. I have started a blog to show the progress. 

To show a simple usage of the API for GCM, I developed a simple test example of a Yesod server, where devices can register to receive GCM messages and users can send messages through the web service.

More information: http://gsoc2013cwithmobiledevices.blogspot.com.ar/

Every feedback is welcome!!

Thanks,

Marcos