I stick with my opinion and say 2011. And I say that because I dont believe that the 360 will ever sell a lot more consoles then 2008 (10.8 Mln). But if the current trend sustains the PS3 will peak this year. I assume 20% higher selling numbers this year for PS3 then last year.
2009: 12 Million(+)*1,2= 14.5 Million 360 should be 10.8 (if Natal has no big effect would still be more then 2009).
14.5-10.8= 3.7 Mln.
Ps3 would outsell 360 by 3.7 Mln this year and the gap would be just 2 Mln which would melt to nothing during first 6 months of 2011.
Maybe I am wrong I speculate that natal wont sell more then 500k-750k consoles this year, which would lift the 360 to 10.8 Million and I assume that PS3 will have a price cut of 50 Euro/Dollar in fall and Arc will have a noticeable effect. And that the current sales trend goes on.