The relevant changeset in Three20 where Joe resolves this should answer your questions:
http://github.com/facebook/three20/commit/8183ae25528bbc575a...
http://github.com/facebook/three20/commit/8183ae25528bbc575a...
See http://github.com/facebook/three20/commit/c62a4cfd26c19d9248...
Waiting 2 weeks for an Apple reviewer to press the "run static analyzer" button sucks.