The problem is that the maximum line length is not implemented in the pep8.py used by pydev. This means that it will not recognize the maximum line length.
If you use '- max-line-length "as you can see in the logs that it is subject to one exception and that is when it is about to parse arguments. If you open the file that the error comes from, one can see that "- max-line-length" is missing.
The log can be obtained through Help-> Aptana-> View Log File.
Check for error in "pep8.py"
To make this work you probably have to ask that they fix this upstream or fix it yourself locally.
Thanks for your answer! I can't see the log file as I don't have the option "Aptana" in Help menu :S It's a pitty that this feature isn't available.
Ok, I forgott that you were using Eclipse and not Aptana. The logfile should then be located in <workspace>/.metadata/.log
+1 Took me some time to realize that too. This answer could have saved me a lot of that time.
@pwagner & Henke I've just included another answer that actually does solve the problem. Cheers!
The current pydev version has a pep8.py that has the --max-line-length parameter!