Interesting, that's not recommended by python devs. Ubuntu follows the guideline of keeping /usr/bin/python as Python 2 (which will not be installed by default), and /usr/bin/python3 as Python 3.

ETA: Arch Linux actually did this before there was an "official" guideline. http://www.wefearchange.org/2012/04/python-3-on-desktop-for-...