Google has made it abundantly clear that we should not be selling links. Their stance has made a lot of webmasters rethink their position on the subject and most are trying linkbaiting and other methods to get around the issue.
One thing Google has not been quite as clear on is what their position is surrounding image adverts. If you look at the square adverts on sites such as BlogStorm, TechCrunch, Search Engine Journal, Marketing Pilgrim all have direct links to the advertiser along with some descriptive alt text. These links will be passing weight to the advertiser and with some keywords in the alt text will help the site rank higher in Google. Sites such as ProBlogger pass the links through a Valueclick redirect so they will not pass any link weight to the advertiser.
Obviously the aim of buying an image ad is primarily for branding purposes but with the current crack down on paid links many are looking towards image ads as a viable alternative.
I assume that we should be placing the nofollow attribute on banner adverts as well but I’m not sure whether Google is as worried about devaluing these links as they are about paid links.
What do you think?