well if its got a deal with google similar to mozilla's it can make a good chunk of change with commissions on searches. mozilla generates well over $100M/year from google deal.
This figure appeared absurdly high to me on first glance, but Wikipedia says Mozilla earned $61.5M from search royalties in 2006. Total revenues were $104.3M in 2009, putting the estimated amount from search at around ~$90M. I don't know that that's necessarily all Google, but still an impressive sum.