With the launch of Google Pay Pay Action ads comes a new Google AdSense ad format named "text link." This has received a bit of buzz throughout the forums and the blogosphere.
What is this new ad format?
The ad will look like a standard hyperlink (<-- as such) but it will also sport a mouseover that shows "Ads by Google". That is basically the only way to label a hyperlink an ad, by using a mouseover of some sort.
Update: I just added a post on AdSense Adds Google Checkout Referral Button and I had a text link unit as an option, so this is what it looks like when you mouseover:
Is this going to be like an IntelliTXT product? IntelliTXT is a product that replaces the words of your content, dynamically, and makes them ads. Several sites you may stumble on, may have this - and I personally find them very annoying. The ads have special colored underlines (that look like hyperlinks) and when you mouseover them, they look like this:
The Google Pay Per Action text link units will not show ads when you mouseover, they will just show "Ads by Google" and if clicked will take you to a page, paid for by the advertiser. Another huge distinction is that these ads won't dynamically replace the words in your content. IntelliTXT is a contextual product that dynamically matches the words on your page, and replaced those words with keyword specific ads. Since this is a Google AdSense Referral product, the ads will not be contextual. So you have to manually replace your keywords with this ad (I am not even sure if a publisher can pick the text they want, I believe only advertisers can) so most of the time you won't be able to work the ad within your content, because the keyword phrase may not make sense to your content.
Can Google easily make an IntelliTXT product? Of course! Have they, I don't think so.
Finally, these text link units will only be found in Google's content network. They will not be used on the search network (i.e. Google.com).
Forum discussion at Search Engine Watch Forums.