Yeah but the non-GAAP numbers exclude customer acquisition costs (e.g. marketing). Not sure why that's excluded as marketing is a continuous and fundamental cost of doing business.
[1] http://online.wsj.com/article/SB1000142405311190363560457647...
[2] http://www3.cfo.com/article/2012/2/banking-capital-markets_g...
[3] http://blogs.smeal.psu.edu/grumpyoldaccountants/archives/530
[4] http://www.scalefinance.com/accounting-finance-and-groupons-...
[5] http://blog.agrawals.org/2011/09/24/groupons-cost-of-revenue...
[6] http://takingpitches.com/2011/06/04/groupon-s1-ipo-marketing...