Looking at the top sellers from ps3 and comparing it with xbox 360 it is clear that ps3 exclusives DO NOT sell that well (compared to xbox exclusives) Here are a few examples:

Uncharted-3.10                                                                                       Gears of war- 6.04mil

Uncharted2-3.13                                                                                     Gears of war 2- 5.66 mil

Killzone2- 2.25                                                                                         Halo 3- 10.93 mil

Resistance-3.68

Resistance 2- 1.85

Halo 3 sold more than Killzone 2, Resistance and Resistance2 put together!!! Why is this? 

ps3 owners more diverse. a lot only bought it for a blu-ray player

Halo is a huge franchise.
PS3 has a smaller install base
Microsoft advertises better
Some PS3s are just used as Blu-ray players.

I agree about the Resistance 2 and especially Killzone 2 part, but I say that Sony is at fault for those games not meeting their sales potential.
Only Gran Turismo can compete with Halo from the PS3 side.
Uncharted 2 is doing fine.

Boggles my mind thinking about it 0.o
Even Michael Pachter said that UC2 deserved 1more PS3 owners buying it lol.
just because its a mazing game.

Many Xbox360 owners pirate their games. - I think this can offset the above bolded reason no?

halo 3 is the flagship title of the xbox 360. Gears of War was the first great exclusive of the 360 and has thus become very popular, just like MGS4 sold very well since it was the first great exclusive on the ps3. PS3 lost exclusivity on one of its flagship titles GTA, and hasn't had any others although a lot of people think GT5 will be it and they're probably right.

lol Patience... 360 just started out with a much bigger fanbase because of its year lead.. Things will majorly change as time continues.

Its a shame though for now because the quality of the ps3 exclusives are just on a whole different level then 360's and do deserve many more sales.

It is wierd tho too, cuz look at assassin's creed 2 on ps3 compared to xbox.. and look at final fantasy 13.. Also, most of the games u compared were back in the day except for uncharted 2.... start the comparisons this year.

Both God of war 3 and heavy rain will outsell mass effect 2.

While we can ignore that last one, once we get GT 5 in there, it might look slightly different. There also seems to be a distinct lack of MGS 4

The question should be : Why are PS3 exclusive not selling as well as 360'S halo or Gears?

Now, if you put Gears in there, you have to put MGS4 which is on its way to 5 million plus.

The only PS3 first party game that really sells a lot is GT and it's not out yet, but notice how PS3 exclusives are getting better and bigger, that's what I care about.