Google glass development kit is already out for download https://developers.google.com/glass/. To start working with GDK you should at have a degree of android development background since it is build ontop for andoids core framework. Aside from developing native codes, I believe the real potential for the glass will be on its Google Mirror API and Web Service features. My two cents on the following for the glass.
1. To reduce cost remove the voice features. Just display the message on the panel.
2. Have a touch sensitive button on the side for the glass.
3. Have a framework to communicate android phone and glass Asynchronously.