tl;dr -- Google contract worth about 100 million in 2010 given the latest public numbers, more than 150% of the total engineering budget.
My rambling notes... I wanted to look into this corporation/foundation distinction to see how much money Mozilla gets from Google. Some highlights from Mozilla's 2010 financial report (2011 isn't out):
http://static.mozilla.com/moco/en-US/pdf/Mozilla%20Foundatio...
1) Mozilla doesn't live off our contributions, not by a long shot: Mozilla only had collected 150k in contributions throughout 2010 and expected at most 1.7 million total (there is a discrepancy in time between when the report is prepared and when donors may actually send the check they promised).
2) Mozilla received 121 million from "royalty revenue" -- anything related to the Mozilla brand: Amazon affiliate programs, search engine branding like this Google deal, and sale of products from the Mozilla shop.
3) According to note 9 (footnotes are always where all juicy info is buried), 84% of the royalty revenue from 2010 is from "a contract with a search engine provider for royalties which expires November 2011." I take that to mean the Google contract. 84% of 121 million is ~100 million.
4) Mozilla's burn rate was 62 million, which means Google paid for the entire Mozilla development effort in 2010. Interestingly Mozilla's burn rate increased 50% from 2009. I can speculate this is from the increased competition from Chrome, but who knows.
5) Mozilla held 105 million -- yes million -- in investments in 2010 (mostly bonds and index funds, check out note 3). Without Google, Mozilla can use this war chest to operate for at least 2 years. That's much, much better than most companies.
6) Last, as a side note: there was a re-org in early 2011 (which I had missed) where Mozilla seems to have folded the thunderbird effort in with the browser team. This could be a "synergy" move, but it likely means they are divesting from that business and putting more people on the browser effort.
Burn rate of 62M is pretty high. That can fund about 300 people plus other costs like hosting. Is that only for the browser or for other projects as well?
300 people is a very low estimate for every single browser development effort on the market right now. For example, Opera had over 700 employees in Feb 2011 according to <http://my.opera.com/haavard/blog/2011/02/01/decade>. I'd be incredibly surprised if Google doesn't have at least several hundred people on just the non-WebKit parts of Chrome, plus the people working on WebKit at Google, Apple, and other places. Microsoft had somewhere between 30 and 50 people working on just the JS engine in IE9, according to unsubstantiated rumors, for what those are worth.
So the short of it is, browsers are harder and take more effort to develop than most people think. ;)
• the agreement appears to be with the Mozilla corporation, rather than the non-profit foundation... but the corporation is 100% owned by the foundation, so the distinction is mainly for tax/accounting/reporting advantages
• the prior agreement delivered over $80 million in yearly revenue to Mozilla (as of the last time I recall seeing credible numbers reported, a couple years ago)
• the prior agreement technically expired 3 weeks ago, so the multi-year renewal negotiations may have had some wrinkles
I hope Mozilla is now earning even more; with the rise of Chrome and iOS they may need it.