Did defaultdict's become not marshal'able as of Python 2.6? The following works under 2.5, fails under 2.6 with "ValueError: unmarshallable object" on OS X 1.5.6, python-2.6.1-macosx2008-12-06.dmg from python.org:

```
from collections import defaultdict
import marshal
dd = defaultdict(list)
marshal.dump(dd, file('/tmp/junk.bin','wb') )

```