You can find everything that Zynga has reported here (particularly p. 59): http://www.sec.gov/Archives/edgar/data/1439404/0001193125112...

When they (Gamautra) say "year-on-year", they actually compare Q2 2011 to Q3 2010, which is not standard; in general, you would want to compare Q2 to Q2 to account for seasonality of demand etc.

You can see that their sales and marketing expenses stayed roughly the same over the last 3 quarters, but there is a huge rise in R&D (almost 2x from Q4 10 to Q2 11), G&A and some small increase in cost of revenue (Facebook credits?).