Many have commented on the event.
As I noted in a reply to Romain Beauxis's post, the only reason Google was the default search engine in Ubuntu, and is still in other distros is because Mozilla has a revenue deal with Google. Which means that actually, Mozilla might be getting money from Debian, Ubuntu and other distros' users actions on the Google search engine. (maybe not from Debian, though, because of the search url including iceweasel instead of firefox). Now, at least, Ubuntu will be the one getting the money.
One has to know that these revenue deals probably don't cost a dime to Google and Microsoft (through Yahoo), because they may be "transferring" revenue they get from the extra advertising revenue they can get from these users being using their search engine as default.
Anyways, much more interesting to know is how Google is going to react on other services: some core functionalities of Firefox (geolocation, safe browsing) are based on Google services. These are actually a possible problem for Debian, depending on the agreement between Mozilla and Google, and I have yet to address the RC bug I filed on my own package about these.
Now, since Google is going to get less advertising revenue from Ubuntu users in favour of one of its competitor, why should they provide the geolocation and safe browsing to these users ?