I honestly think that the PS3 will not be able to catch up to 360 in terms of sales, Because 360 have had a 1 year sales advantage, that alone already determines that the PS3 can not outsell the 360 overall. I also think the gap may increase this year and next year if Microsoft does the right type of advertisement for Halo Reach and Project Natal, In 2011 Gears of war 3 is going to be Big.
Although you have to be impressed with how well the PS3 is selling despite being priced higher then their competition, its an amazing accomplishment to be outselling the MS 360 when it is so much cheaper. Although this may contradict what am saying but there is still a chance for PS3 to exceed 360 in terms of sales but this would most likely be a long term thing.
EDIT: Halo Reach will definitely sell millions! but will it really sell Consoles? since its established Halo Fans have already owned a 360 consoles, Project natal, I pretty much do not know what will happen with Natal.. Will it have a success like the Wii? Maybe? High Risk High Reward, If it does not work out then Project natal is pretty much FAILED
Also Gran Turismo 5, My favourite simulator on consoles. Am starting to doubt that it may struggle to see success as it predecessor did, To begin with PS3 owners are known not to buy much games but there has been an improvement, Many GT fans probably moved to 360 and are playing Forza? So much doubt but i really hope Sony do market this game correctly to be able to sell millions in short amount of time and be able to shift consoles.
I will still stick with my OP, Sony won't be able to outsell 360 Overall but will do so in a Long term, Probably when the generation is over