Creating a file Test.hs:

import Foo
main = print "hello"

where Foo does not exist, used to give a really nice error (with 6.8.3) but with 6.9 and 6.11 gives a horrible error message:

$ runghc Test
*** Exception: Could not find module `Foo':
  Use -v to see a list of the files searched for.
$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 6.11.20080929

Compared to version 6.8.3:

$ runghc Test.hs

Test.hs:2:7:
    Could not find module `Foo':
      Use -v to see a list of the files searched for.

A much nicer error, importantly saying where the import was - in my case the import was in an imported module, so I didn't even know which file was causing the error.