I think it has to be Blu-Ray.  I've met the most random people talking about the PS3 they just bought - people who have never owned a system before, and ones who really have no intention of playing games, really.

Quick comments on above posts: 

I agree with the idea that GT5P is NOT a top 5 game.  It's not even the full game and has an 81 metacritic average.  The only one that's a surefire top 5 game there is MGS4, and that may be top 5 critically but not commercially.  Gears will sell more, as will Madden, GHIII, SSB Brawl and likely some others, like possibly Fable 2, that is expected to do well but comes out as a game way beyond what we expect (just as an example - who knows with Fable?).

 I don't think it's possible for a PS3-exclusive game to be a top 5 seller this year yet.

Well it depends on what you mean by top 5. If it is top 5 favorite games than you are right it would be a matter of opinion. Anticipated would be debatable though there definitely some on the PS3. In terms of sales the answer is no.

Wii Fit, Super Smash Brothers, GTA IV, Gears of War 2, and maybe MGS4(which will be critically acclaimed but I suspect that there will be a sleeper hit as usual). Will be the top 5 selling games. I suspect GTA IV will be the top selling game for 2008 when both consoles are taken into account and it will have decnet legs. I expect Wii Fit to be all about the legs with a few push ups in between and maybe a balancing act. I suspect Gears of War 2 to be very frontloaded but coming in with a bang and Smash brothers well we are already seeing that.

I do not expect much out of MK Wii in comparison. I think it will sell well around 3-4 million but it doesn't have the hype SSBB did or Wii FIt will for that matter.

It's a combination of the Blu-ray victory, and upcoming games for '08, IMO.

Blu-ray, upcoming games and no RROD.

one way or another though, more consoles = more consoles

 Yeah that's pretty much how I see it.

Im not so sure MGS4 is going to be outsold by Gears 2 anytime this year. Eventually it may be very close, but by the time Gears 2 is released, MGS4 will be selling strong in every region in the world, and the PS3 install base will be within 4-5 million of the 360.

Gears 2 isn't going to sell as many copies as Halo 3, thats certain. By the time Gears 2 is released, MGS4 will have atleast 3,000,000 sold WW, and still be selling strong. Judging from initial impressions its going to be epic in every way including graphics storyline and gameplay. So new comers will eat it up, old fans must have this game because its a finale, and finally Japan has a huge game that it likes along with the US.

So really im going to come out and say it. MGS4 will sell more copies by years end than Gears 2. Its the first game with a global release date on the PS3, and the first game that actually appeals to the entire install base. MGS4 won't have any competition at all until November.

Short summary of why PS3 is doing better then, well... Before.

1) Blu-Ray has won the HD Format-war. a 400$ Blu-Ray player which can play HD games is very attractive for new Blu-Ray buyers.

2) 400$ pricepoint is more 'accesible' then the 600$ one, or the 500$ one for that matter... Still, it's nowhere near where Sony wants it to be, thus you can still see the big diference between the sales of the Wii and the PS3... (PS3 has way better tech for it's price however).

3) X360's high failure-rate and the loss of HDDVD causes a lot of 'potential' X360 buyers to eventually go with a PS3... This is also due to the prices getting closer to eachother in the US (price hasn't dropped there yet for the X360).

4) PS3 was doing so bad last year that it could only go better...

5) Line-up is much stronger. Sony had the time to release a couple of strong first-party titles... Combine that with the fact that 3rd-party developers have been able to succesfully use the PS3's power and handle the architecture and you have more reasons to buy a PS3 then ever before!

Im with you Jandre...did someone say that MGS4 was too niche and Fable 2 would out sell it? Talk about niche.

This is the best game to come out for the PS3 and people are going to eat it up.

OT: Blu Ray is certainly helping but PS3 is starting to be seen more in more in popular culture rather than just for hard core gamers

I would say it's a combination of the press not taking digs every time possible and blu-ray. It looks like the console is here to be a strong contender in EU and NA. Unfortunately, not Japan.