It's old school IFraming. One group did it a few weeks back and I can see the page on their site that contains the iFrame listed as a referrer in my Google analytics.

I don't imagine it would cause a duplicate content issue since the pages are being read from my domain (through the iFrame) but I can't say that I am positive about that.

We have a new site that is a great resource for a serious subject (suicide). I have been getting many requests from various communities and clinics about help on embedding our site in their websites.

Although I certainly don't want to keep this resource from being used as much as possible, I am curious about the SEO costs/benefit to having someone embed our site on their own website rather than provide a link to our website directly from theirs.