I've successfully back ported the bytearray type and the io module from 3.0 to 2.6. The code is available in the branch trunk-bytearray . I'm down to four failing byte tests and one failing io test. The failing byte tests are all related to pickling and subclassing.
I like to get the remaining tests fixed for the upcoming release in a week. Please checkout the branch and help me figure out the remaining issues.