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I asked the same question and was told 'Probably not', if that helps.
"If you are working on your own machine, you will probably need to install Python. We will be using the standard Python software, available here. You should download and install version 2.6.x, not 2.7.x or 3.x. All MIT Course 6 classes currently use a version of Python 2.6." Copy and pasted from the assigments site. Even if you are able to the same things with a newer version it is clearly stated to use a 2.6.x version.
Honestly, it wouldn't make much of a difference. Python 2.6 and 2.7 has no syntax changes (the only difference you need to care about is the mutable set literal, backported from 3.1). In short, you can use 2.7 or 2.6, just not earlier versions or the 3.x line.
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Python 2.X is forced to have backwards compatibility with all previous 2.X versions. The lack of BC is why Python 3 is such a flop at the moment. The instructions were because most people don't actually have Python installed on their machine by default. Specifically stating not 2.7 was because it includes features not included by 2.6. Therefore, you may end up using built ins and functions not included with 2.6, crashing your code when their automatic code testing tries to run it for grading.
Having bumped into some of the limits of code academy's automatic code checking in the past I'll do a down shift to 2.6. For an automated checker it does a great job but I've had it bork on me even when the code was correct. My real interest is Python 3.X and that's where I'll do any real project work in Python. However having a good overview of 2.6 or 2.7 can't hurt and as KennethSills pointed out 3.X is still in the process of being incorporated into the larger community.