By that token, the pre-installed search sites are ads. There's big money associated with those things, yet I haven't heard anyone complaining about them.
I like the look of this new feature—I think it will be more useful to beginning users, it produces a nicer first-run user experience, and it gets out of the way very quickly.
I'm not sure if people think that Google Chrome has ads like this or not—to my view, the whole product is laced with ads for Google products, far more intrusive, obnoxious and anticompetitive than anything Firefox has been able to produce.
(You might guess that I'm a Mozilla fan. That perception would be accurate.)
The pre-installed search engines are ads. They [Mozilla] are being paid to promote a product [Google Search]. That being said, it is not a form of advertisement that is particularly obtrusive, and it is "opt-out" - you are not prevented from removing search engines from the drop-down list if you so choose.
I personally take objection to ads when they take away from the usability of the product, when they are of a form that could be used to infect my computer, and/or when they are of a form that can be used to pass on data to third parties. (Un?)fortunately, this covers the majority of advertisements on websites: a large chunk of ads are pop-up, pop-over, are flash (both for battery life and exploits), redirect to untrusted websites (exploits), and/or use content hosted by third parties.
As such, my worry for this is: what happens if someone buys a spot that takes you to a page that exploits your computer then redirects to (for example) facebook? I hope that the bar (price for a spot) will be high enough to discourage this, but I don't know...
I'm not implying I have a problem with Mozilla including these ads. If it helps them out in the end to keep the browser field competitive, I'm all for it.
I also won't argue your point about calling the pre-installed search engines as ads--but they have a utility to them. The upcoming ads are going to have a hit or miss utility. Either I frequent that sponsored site, or I don't and find it to be a waste of space on my new tab page until it gets filled out by another site.
I think if anything, I'd just be worried that this is a slippery slope for Mozilla. These new sponsored site listings seem completely un-intrusive for now... but could it go further in the future?
I think it is a really clever way to do advertising because it allows large companies to give them a bunch of money and at least get something for it that they can show investors while not annoying users much at all. This is most likely aimed at companies like Facebook and Google and Yahoo that have no real need for advertising as such but are willing to spend money to make their services seem even more identical to the intenet itself (for less tech savy users). The company would most likely already recognize that Firefox is important for people being able to actually use their services but the extra bonus of a link to their company could help convince anyone who is doubtful that they should spend money on open source browsers (and gives them an extra spot in the budget they could put such a contribution). Overall a good move on Mozilla's part IMO.