Adam Powell posted a series of posts to his Google+ about the new navigation drawer design pattern (which is getting adopted really fast). The posts over a wide range of topics. In the first post he covers the design principles and thought processes of the Google's team developing the design pattern based on the existing implementations.
The second post covers things like the navigation drawer's relationship to the action bar as well as gestures and discoverability.
In the third post Adam explains the use of the navigation drawer icon use and how the navigation drawer became different design pattern from the sliding pane layout used in the new hangouts app.
The fourth post talks about discoverability and and a bit more about the relationship between up and navigation drawer.
I really enjoyed the glimpse to the Google team's thought processes and greatly appreciate that Adam allowed us to gain a bit more insight to the new design pattern. If you haven't read the posts yet I highly recommend that you do. They explain reasoning behind many of guidelines which might not be immediately obvious from reading just the design guideline documentation.
Part 1: https://plus.google.com/+AdamWPowell/posts/2zi4DXd3jkm
Part 2: https://plus.google.com/+AdamWPowell/posts/VdgexsZeXHW
Part 3: https://plus.google.com/+AdamWPowell/posts/8j2GVw72i1E