Neil, and others,
Does the cabal file for Tagsoup require a version of Cabal newer than 1.1.6? In case it does it doesn't say so. I suspect this is the cause of the rather cryptic error message: "setup: tagsoup.cabal:20: 'Executable' stanza starting with field 'ghc-options'".
I also noticed that the Haddock-umentation on Neil's side is for version 0.1, while Hackage has version 0.4. I was rather confused by that at first, since the module names had changed :)
/M