Which Version of Python to Use for Maximum Compatibility
<p>If I was going to start an open source project using Python what version should I use to ensure that the vast majority of users can use it on their system?</p>

<p>I'm the kind of person who quickly jumps to the next version (which I'll do when Python 3 comes out) but many people may be more conservative if their current version seems to be working fine. What version would hit the sweet spot but still allow me to enjoy the newest and coolest language enhancements?</p>

<p>As python is in kind of an transition phase towards python 3 with breaking backward compatibility I don't think it is a good idea to go python 3 only. Based on the <a href="http://www.python.org/dev/peps/pep-3000/#timeline" rel="nofollow">time line</a> there will be at least one or two following releases of the 2.x series after 2.6/3.0 in october.</p>

<p>Beside not having python 3 available on your target platforms, it will take some time until important external python libraries will be ported and usable on python 3.</p>

<p>So as Matthew suggests staying at 2.4/2.5 and keeping the <a href="http://www.python.org/dev/peps/pep-3000/#compatibility-and-transition" rel="nofollow">transition</a> plan to python 3 in mind is a solid choice.</p>
