What's the attach rate on both systems? The people I know who have both systems rarely touch their PS3s. The 360 gets played while the PS3 collects dust. Saying Sony wins because they sell a few more systems that don't get played is silly.
I had a grad school class on the managment of technical operations where I had to profile a company. I picked Activision and spent a lot of time digging around in their SEC annual reports (form 10-k) to compare their financials to EA. In both companies' reports they break out revenue by platform which seems to me to be the better indicator of which one is "winning". Even though I think it is kind of silly when people get all worked up over a game console. Anyway here is the chart and a brief table. All the data is available via the SEC and the EDGAR document system.
EA+Activision Revenue Totals (in Millions)
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2010 - Xbox 360 ($1,901) PS3($1,625)
2009 - Xbox 360 ($1,862) PS3($1,360)
2008 - Xbox 360 ($950) PS3($523)
2007 - Xbox 360 ($515) PS3($116)