There are lots of assumptions made here on both sides by fanboys. Someone who has the time can make a reasonable guess as to what it will take for the PS3 to overtake the 360 in total worldwide sales with just some time and math calculations. I'm not going to but someone here I'm sure has more time than me so knock yourself out.
Points to consider:
1)360 will very likely outsell the PS3 in the U.S. rather significantly through the end of the year due to price cut and a handful of major exclusives.
2)360 isn't going to increase by any real margin in Japan any time soon (or probably ever)
3)The PS3, unlike what everyone says, isn't killing off the 360 in Europe. It had a great launch, but that has to be discounted and trends need to be factored in.
4)Yes, the PS3 is going to get cheaper but so is the 360. You can't keep saying that once the PS3 gets cheap enough it is going to "own"
5)Contrary to popular belief that the next gen HD movie format is won, it isn't. There are announcements every day that swing it both ways. It really doesn't matter in the end, though, as the majority of people buy their systems to play games. (The Joe Six Packs of the World and not the early adopter hardcore).
So... take recent sales histories, take out your fanboy beliefs, project forward a bit and it is going to come down to, in my opinion, U.S. beating PS3 for the forseeable future, Europe split *fairly* close over time, and Japan solidly behind the PS3. How long will it take, then? Just for fun, a monthly moving average (say 3, and 6 month MAs) projected forward would be interesting. Not scientific, but interesting none-the less.
I hate trolls.
Systems I currently own: 360, PS3, Wii, DS Lite (2)
Systems I've owned: PS2, PS1, Dreamcast, Saturn, 3DO, Genesis, Gamecube, N64, SNES, NES, GBA, GB, C64, Amiga, Atari 2600 and 5200, Sega Game Gear, Vectrex, Intellivision, Pong. Yes, Pong.