The heart of the issue here is the distinction between content sites and aggregators, which can seem blurry at times but in practice is quite stark. The symbiotic relationship between these two classes of site has evolved over the past fifteen years or so, and should perhaps be formalized—in the HTTP spec, even, it seems to me.

As our means of collecting, processing, and re-filing information multiply, I see no inherent reason why you shouldn't look at one site through another. In the 90s, the word "portal" was popular for aggregator sites, and the metaphor is useful: Digg is not a content provider, but a window through which content is found. So a framebar may in fact be a perfectly natural expression of that removed yet enabling position. You look over the sill of Digg into pastures of Engadget, CNN, what have you.

And if the complaint is in fact about SEO link credit, then can't this be solved with richer metadata at the HTTP layer? It seems to me that what's missing is just one HTTP Header. Call it "Content-Source": as part of a 200 response, it's a URL which the browser will not redirect to, but to which the spider will. This way, the spiders credit the correct link, while the user gets the rich experience of viewing one site through another. If this is really about which URL you see in your browser bar (and honestly, is it really about that?!), the browser could have a responsibility to display the "Content-Source" URL.

The nay-sayers and framebusters are bringing in a lot of 90s baggage about what the internet is "supposed" to be that's not very meaningful today. Some of these complaints ("if we let Digg get away with it, civilization will begin a long downward slide") have a bizarre Hobbesian ring to them. "Frames of frames" don't sound dystopian to me so much as they sound apt.

(My thinking on this has much to do with NewsTrust, a news-rating site I develop, and which we very much hope to be a window onto the greater news stratosphere.)