My “Under the Loupe” tutorial on using an export action to create a custom watermark for the web galleries is finally out in Photoshop User magazine (Sept 07, pg 84). Here’s the nutshell version:

1. Create watermark action in Photoshop
2. Turn action into a droplet and save in Lightroom’s Export Actions folder
3. Configure Lightroom’s Auto Import function so that images saved from the droplet are automatically imported
4. Select images in Lightroom that you want to watermark, click Export and select your droplet as the “After Export” action
5. Bring all the auto imported watermarked images into the web gallery
6. Upload to your web space

Pick up the September 2007 issue of Photoshop User magazine for the detailed steps!

UPDATE: You should also check out an alternative method I find even better! See how I watermark photos in Lightroom 2 on my Lightroomers blog.