I have just finished a survey article on pairwise (and higher levels
of interaction) testing based on combinaorial designs. For those who
followed the AETG discussion on this site earlier in the year - you
may find this article of interest.
It is at
http://www.haifa.il.ibm.com/projects/verification/gtcb/papers/combinat
orialFinalDraft.pdf
I am happy to receive feedback...