Completely agree. tchrist's Style Guide has this to say on the subject and includes this absolute gem from Dominus:
The appropriate length of a name is directly proportional to the size of its scope.
which, together with tchrist's philosophy that clarity trumps length (to which I also subscribe) I think sums it up nicely. It's also worth pointing out for completeness that such matters of style apply to any names in source: subs, packages, constants, variables, etc.
It's fair to say that this advice is perfectly generic and applicable not just to Perl.
