My travel schedule remains insane, and I notice that thinking about 'hard' problems is very difficult while travelling. Sigh. Anyhow, those that had beer with me in the last year and a half or so know that I have a severe interest in OBDD-like structures and their applications to cryptanalysis.
So I just wanted to put a reference here to
http://eprint.iacr.org/2006/072.pdf