I noticed on my package's hackage page there is a build failure message: http://hackage.haskell.org/package/txt-sushi
I don't know if these are real errors or not (I don't experience them on OS X and it's pure Haskell code) but I did poke around and noticed that some popular packages on hackage also have build failures:
Just as an extra data point, I've found that some of the build errors on Hackage are due to the machine's build state and not due to any intrinsic failure in the package in question. Furthermore, Hackage does not generate Haddock for these packages even though generating Haddock would still be 1) possible and 2) useful. I think it would be better to divorce the build process from the Haddock generation, since they aren't necessarily related (and Haddock builds will fail if the package *is* trivially broken.) -- Jonathan Daugherty