Google has made a $2,000,000 donation to the Wikimedia Foundation, the organization that runs and maintains Wikipedia. That's not why Wikipedia is here to stay. They have been asking for donations for awhile now. That's instead of taking on ads - which would definitely bring them some serious income - even if they just ran Google ads.
What is significant is that Google tried to create its own version of Wikipedia called Knol which launched back in the summer of 2008. Knol has not had any real impact on Wikipedia or on users. When I first wrote about Knol, I said one of the complaints teachers have with Wikipedia is that you don't know who wrote the article (probably many people) or what their "authority" is in the subject. Some are written by experts, but many are written or revised by simply interested folks and then possibly reviewed and edited by someone with some expertise. Knol tells you who wrote the article and their qualifications right on top.
A year later, I did another post on Knol (BTW, a "knol" is their "unit of knowledge" term). Although it differed from Wikipedia by saying who wrote the article and their qualifications, and Google had started with an invited group of writers who know a particular subject, the project never caught on.
I think the donation is a kind of concession that Knol failed.
Even teachers who had problems with students using Wikipedia because of the unkown authorship and "authority" of the content, did not send their students to Knol. I don't think I ever heard a teacher mention it , and I suspect that if you surveyed teachers the vast majority would not be able to identify Knol at all.