TUAW reader Eric F sent in a note letting us know that "Safari Adblock allows you to watch Hulu programming completely commercial free!" I gave it a try. I downloaded a copy of Adblock from its SourceForge repository, installed it, activated it, and fired up Hulu. A nearly complete episode of Buffy later, I can confirm that I wasn't shown commercials.
I haven't give this enough of a test obviously, to be able to say decisively one way or another -- especially since I don't regularly use Hulu -- but the news is promising enough that I thought I'd share. Let us know in the comments if this solution works for you.