Listened to another photography podcast a week or so ago, posted about it here:
http://www.photography.ca/Forums/showthread.php?t=4429
This Thomas Hawk fellow had an interesting take on his photos. He posts everything to Flickr, full resolution. He knows people will steal his photos but he also has made enough money from honest people asking to buy his photos to fund his photography habit.
The only way to truly protect a photo online is to not post it. You have to decide for yourself if you want to hide your photos or share them. I've decided to share them and if someone wants to steal them then I'll deal with that if I ever find out about it. Hopefully, they'll just be enjoyed by people who get to see them. And if I'm really lucky I might make a couple of bucks.