So apparently OSX Lion and Vim plugins implemented in python are not playing well together.
Calls to sys.stdout.write() and sys.stderr.write() appear to be crashing vim core. I say appear becauses it nearly impossible to debug. Rather than bang my head against the wall all night or do some brew compiling gymnastics, I just switched the stdout/stderr calls to use an even more pythonic style:
print >> sys.stderr, 'Blah'
Works great. Get your fresh code fixes here.