StoutFiles - 1:37 pm on Mar 28, 2012 (gmt 0)

The opt-out meta-tag is a joke, I can't change thousands of web pages...

Why aren't your pages displayed dynamically? You should consider attempting that regardless.

They have to come up with a way to opt out entire websites.

They probably won't, Pinterest (like YouTube before it) benefits from stolen content. There are other methods you could use like watermarking, but yes, most image sites have opted for paywalls. The internet is still too much like the Wild West, if you put content out there, prepare for it to be stolen.