For working with CQL, I suggest using the new DataStax Python driver. (Disclosure: I'm the author of the driver as well as the maintainer of pycassa.)
Pycassa only uses the normal Thrift interface, which cannot interact with all types of tables created through CQL, only COMPACT STORAGE stables. You can see more details about Thrift vs CQL3 if you're interested.
Also, I think you'll like the more advanced connection pooling in the new python driver.