Thus spake Lutz Horn (tichodroma@posteo.de):
I've tested TorBrowser-2.2.37-1-osx-x86_64-de under Mac OS X 10.7.4 on an iMac with a 2.5 GHz Intel Core i5 CPU.
- Evercookies remain (windowData mechanism) even after deleting the whole cache and using a new identity
It turns out Lutz was using Vidalia's "New Identity" here rather than Torbutton's.
Technically I'd call that a dup of this UI/usability bug: https://trac.torproject.org/projects/tor/ticket/5277
Hopefully the TBB-alpha series will make mistakes like this less likely. If you have better ideas, commenting on tor-talk or tor-dev are probably the best places. Or file a new bug.