Should runghc use PATH?

Folks,

runghc (new in GHC 6.4) currently searches for a GHC binary to run in
$PATH.  Brian Smith asks whether it could use a specific GHC binary,
namely the one that it was installed with.

We can do this on Windows, but not on Unix (it requires baking in the
path on Unix, but runghc has to be a binary, so we can't do this).  Any
opinions?

Cheers,
        Simon