It is currently undergoing the "big rewrite" (which includes some proper classification work rather than shooting in the dark), however, but it's still in daily use on several sites. Hopefully I can learn a few lessons from Diffbot!
I should also point out BoilerPlate - http://code.google.com/p/boilerpipe/ - an interesting Java based content extraction project that's being worked on an by an actual PhD student rather than a dilettante like me ;-) Again, Diffbot's stuff goes a lot further than this but there are lessons to be learned nonetheless.
Last but not least, a paper by the aforementioned PhD student called Boilerplate Detection using Shallow Text Features is available at http://www.l3s.de/~kohlschuetter/boilerplate/
I suspect that there's going to be a lot more work in these areas in the medium term because of the growth of the "e-discovery" market and because the dreams of a consistently marked up "semantic Web" have been washing down the pan for a while now.