Not exactly new anymore, but perhaps worth considering for some of the current weblog spam fighters. I agree with Mark on many points: simple filter lists are the dumbest idea you can have when fighting spam, regardless of the medium. The fact that these filter lists are being positioned as a great new idea in the weblog space again is truly amusing.
It seems we humans are programmed not to believe that even the hundredth reinvention of the triangular wheel is still a stupid idea...