Now the Google have released the Google Glass- Mirror API, we could start developing Google Glass software.
We have got two quick start options for developing: one in Java and the other in Python. for a start check on the overview page of the Mirror API and go through the four videos that explains Managing timeline cards, Interacting with menu items, Subscribing to timeline notifications, and Sharing to contacts. Also check upon Working with user location. Go through the Developer guide sections for more details. Also check on the timeline section for code examples with convenient tabs to switch between HTTP, Java, or Python.
Google Mirror API Overview