I'd be interested in hearing trends about text-ad blindness. I know I look at and click adwords ads (and adsense ads) a LOT less than I did when they first came available... Especially since Google sold out their ad relevancy and allowed wildcard purchases or unrelated purchases (like ebay showing up on virtually every search with a "find SearchQuery and More at Ebay!!1!!1!"
The more an ad looks like a native site component, the more users will look at it
For all his wacky buildup about the ethics of disclosing such a fact this was a pretty sorry payoff. It is exactly what I would predict from the results of such a study. For something to be insidious enough to consider not telling the public about it I would expect it to at least be both born out by empirical evidence AND counter-intuitive.
It seems like it ought to be easy to fool the user's unconscious processes that determine fixation while still making clear at a conscious level what is and is not an ad. For example, match the color scheme and typography of ads with the rest of the site, but clearly label them as "sponsored links". While it's possible that you might annoy users this way, it would be a real stretch to call it unethical.
This information is pretty unsurprising. That said, I think Nielson is discounting to some degree the effect of good typography/page layout in this discussion.
Pages that are designed well will focus the attention of the audience on the content being delivered. Note that the users also aren't looking at other things that seem to be accessory, like the navigation panes. In the end, though, that's just another argument to try to blend ads into the content area of the site, ethical or not.
