Not so's you'd notice, no. If you want to do small-scale UI, you can probably use AppleScript widgets (my understanding is that they can be called through the shell), but larger-scale items do not appear to be available.

The inestimable Pudge Nandor says

It would be nice to, at some point, have the Toolbox modules (Mac::Windows, Mac::Events) Carbonized so the same GUI-based MacPerl programs would run on both platforms. This may happen in the future.

Which I think answers the longer-term question, too. Right now, I suspect all of his available energy is going into MacPerl 5.6 (whence that quote), but others may be working on the toolbox modules... the Perl on OS X mailing list might be a good place to look. Just on a cursory glance, there seems to have been at least one thread on the subject of GUI widgets--I'm sure there have been/will be more.

Good luck!

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If God had meant us to fly, he would *never* have give us the railroads.
    --Michael Flanders