Python-2.7 has been releases and will be the last 2.x official release of python. So it is time to switch to python-3.x as our /usr/bin/python and python-2.7 as our /usr/bin/python2. See http://wiki.archlinux.org/index.php/DeveloperWiki:Python_Todo_List for all the details about how to achieve this.
What's the rationale for making Python 3.1 the "main" /usr/bin/python? A great deal of python modules still don't support 3.x, there's no WSGI standard for 3.x either so you can't make web apps (and hope to deploy them). Even less C modules are 3.x compatible, and then even less applications. And 2.7 is here to stay for a long time. I think it would be wiser to stay with 2.7 as the main python for now. And maybe switch after Python 3.3 comes out. By that time the 3.x series should have enough improvements to motivate people to port to 3.x -- damjan