Targeting Online Ads to a User Session

Merrell Ligons has come up with a new idea for targeting ads on a web site. As you know, it often takes repeat exposure to get a consumer to notice an ad and recall the company. Merrell suggests that, instead of exposing a site visitor to multiple ads, why not show them just one ad for their entire user session?

What if an advertiser was able to sponsor user sessions instead of buying impressions? For the less technical folks, what if we could guarantee an advertiser that as long as someone is on a website their ad or ads would be the only ones displayed. You could even have a series of banners that displays in succession as the user clicks through the website. 

Now, would that be a cool user experience or just spooky? Anyone offering this type of targeted advertising already? I think the idea has a lot of merit, assuming your visitors tend to read more than just one page per visit.