Hi David,
Chirp is written for Python 2.7, which is why you're seeing the error. Dictionary comprehensions were introduced with 2.7. It's possible that you're just unlucky in trying to use a driver that uses a 2.7 feature, but given that 2.7 is the target version, it's also quite possible that you'd run into more problems if you worked around this one. (If you wanted to try, google for dictionary comprehensions in 2.6, but don't be too surprised if you hit something else shortly thereafter.)
That 2.7 is the target platform isn't well documented. There's a note in the wiki for a Win32 dev env that says "chirp is currently written for Python 2.7 and above", though in the same para it also says it "will generally run on Python 2.6.x". That latter likely depends on the features you want to use. The KK7DS Python runtime for Mac OSX, needed for Chirp on a Mac, is also a packaging of Python 2.7.
Martin.
KD6YAM