Another article about spam. This time, the Reg notes that the arms race between filtes and spammers is escalating. This time, they say that subject lines are becoming easy targets for filters, because spammers are competing with themselves - and coming up with more and more absurd subject lines that are easy to filter out.
I think that once a subject-line hack against Bayesian filters is found, there will be another massive burst in spam - because it will again lower the costs of spamming. You could see
our proposal to end spam for an economic approach to end spam, rather than a technological one.
It cites this (very good) report on filtering techiques and their effectiveness.