[ot]

I had the same problem with sort:

  $ sort <<EOF
  > Aa
  > aa
  > Ab
  > ab
  > EOF
  aa
  Aa
  ab
  Ab

I was going crazy because I was getting different results in OSX and Ubuntu. Setting the LANG to POSIX fixed it.

[Macha]

    $ sort --version
    sort (GNU coreutils) 8.14

For what it's worth, this gets me the same results under LANG=C and LANG=en_US.utf8