Python: Google App Engine source uses tab depth 2
It's miserably bad style.  2-space indentation is simply unreadable.  Don't copy it.  Never use less than 4 spaces to indent in any language.
(Don't assume that something is good simply because Google source is doing it.  If you've ever spent some time looking through the Android source you'd know that there's as much incompetently-written code developed at Google as there is at any other company.)
Looking through the Google App Engine source, I noticed that the tab depth is 2 spaces instead of the conventional 4. Is there some wisdom behind this, or is it just someone's preference? 
(Maybe it's trivial, or maybe Google knows something that isn't immediately obvious.)
UPDATE I wasn't suggesting that it ran differently based on the tab depth. But perhaps there's a good reason for their style.