Using ArcPy to determine ArcMap document version?

I know this question is a few months old, but I'm posting this in case it helps others. I developed this kludge to parse version numbers from MXD documents. It basically reads the first 4000 or so characters of an MXD document and searches for a version number. I tested with MXD versions 9.2, 9.3, 10.0, and 10.1.

import re

def getMXDVersion(mxdFile):
    matchPattern = re.compile("9.2|9.3|10.0|10.1|10.2")
    with open(mxdFile, 'rb') as mxd:
        fileContents = mxd.read().decode('latin1')[1000:4500]
        removedChars = [x for x in fileContents if x not in [u'\xff',u'\x00',u'\x01',u'\t']]
        joinedChars = ''.join(removedChars)
        regexMatch = re.findall(matchPattern, joinedChars)
        if len(regexMatch) > 0:
            version = regexMatch[0]
            return version
        else:
            return 'version could not be determined for ' + mxdFile

Here is an example of scanning a folder for mxd files and printing the version and names

import os
import glob
folder = r'C:\Users\Administrator\Desktop\mxd_examples'
mxdFiles = glob.glob(os.path.join(folder, '*.mxd'))
for mxdFile in mxdFiles:
    fileName = os.path.basename(mxdFile)
    version = getMXDVersion(mxdFile)
    print version, fileName

Which returns this:

>>> 
10.0 Arch_Cape_DRG.mxd
9.2 class_exercise.mxd
9.3 colored_relief2.mxd
10.1 CountyIcons.mxd
10.0 DEM_Template.mxd
9.2 ex_2.mxd
10.0 nairobimap.mxd
10.0 slope_script_example.mxd
10.1 TrailMapTemplateBetter.mxd
10.0 Wickiup_Mountain_DEM.mxd
>>>

The function below is based on Ryan's idea, but is a little more direct. ArcGIS map documents are actually OLE documents, which can be parsed with the oletools module (available on pypi: https://pypi.python.org/pypi/oletools). The function opens the file and reads the version string. Tested with 9.0, 9.3, 10.1 and 10.3, but should work with anything (not sure about 3.x...).

from oletools.thirdparty import olefile

def mxd_version(filename):
    ofile = olefile.OleFileIO(filename)
    stream = ofile.openstream('Version')
    data = stream.read().decode('utf-16')
    version = data.split('\x00')[1]
    return version

if __name__ == '__main__':
    import sys
    print(mxd_version(sys.argv[-1]))