If you use Lightroom and Zenfolio you’ll want to check out this post – “Lightroom 1.3 & Export Plugins for SmugMug and Zenfolio” – on Jeffrey Friedl’s blog. He’s written a plugin for Lightroom that will allow you to upload images directly to Zenfolio.
Of course if you haven’t got a Zenfolio account you can get a $5 dollar discount if you sign up with my referral code – NFF-NSE-63Z – 
Update: The download page for the Zenfolio plugin is here.
Excellent article, bookmarked for future referrence