It's not an ad because it's an organic search result, which is directly relevant to what I'm searching. It's essentially the same as Google Image search result, only better suited for this particular page and request.
Care to elaborate on how its better suited? Why return what you are calling image results on a page that historically has been text only, especially when there exists a perfectly functional Image Search already?
Plus, why insert an image at all if not to convert people that would otherwise miss (or not be looking for) the text result?
> Google said that it won't be charging more for the banner ads - which take up large parts of the screen: "they are part of AdWords" [from the linked article]
"they are part of AdWords" -> Google considers them to be an an ad.
Ads doesn't, per definition, need to be irrelevant.
