AttributeError: 'module' object has no attribute 'SerialException
Additional point for GAE users - try flushing memcache. Somehow ran into this and got stumped for ages after moving a model to a different file. Not sure what was cached that caused it, but it flush fixed it.
I'm adding this solution for people who make the same mistake as I did.
In most cases: rename your project file 'serial.py' and delete serial.pyc if exists, then you can do simple 'import serial' without attribute error.
Wow, didn't see that coming. Spent 45 minutes pulling hair out.