The gaming industry is similar to the computer industry in that software compatible with one device (PC) is incompatible with others (Mac).  A separate version of that software has to be encoded for the other system. However, we're starting to see some game discs, like Guitar Hero, specially programmed to be able to run on either a Mac or a PC.

What I'm wondering is why we haven't seen this with game consoles.  Obviously, the Wii can't use the same disc as the PS3/360 games, as it requires a completely different set of textures.  But with PS3 and 360, their textures are essentially identical, and the games (multiplat) are essentially identical.  PS3, while it uses Blu-Ray, is capable of reading games from a DVD.  Programming for a specific console (such as telling it how to load data, and from where) take up a miniscule amount of disc space.  So why haven't we seen discs that contain the programming for both the 360 and the PS3, that are playable in either one?

Seems natural to me, as devs wouldn't need to estimate how many of each version to ship out--people just buy the game and play it on their system of choice.

It's a good idea but it would take some work if it could be done. I imagine most engines out things in packages and you would just need to make something that could read the package and convert it to something that the PS3 or 360 could read.

That said, I don't know if that's possible and I assume it would eat up processing time since you would have to convert the data on the fly.

Because third parties have to pay each console maker a fee for putting games on their platform. Any disc that could be playable on both Xbox 360 and PS3 would have pay double the license fees.

Well if the ps3 was able to read the Xbox 360 discs what would be the point in buying a Xbox 360 same can be said for the ps3. I highly doubt it will suffice.

That's a good point too, didn't think of that.

And I imagine these discs would just be double sided DVD's (since I'm assuming you can't have one side DVD and the other BluRay) so you wouldn't have to worry about the PS3 reading 360 discs and vice versa.

So it makes more sense to buy a version that can only be played on the Playstation 3, even if it's identical to the version that can only be played on the 360?

@Twesterm and Kilus: Good points--hadn't thought of those.  Nice catch on the royalties, Kilus.  

Edit: I don't think you understood my question, Snake2.  If you're going to make your game exclusive, then go ahead and make it exclusive.  I'm talking about the 90% of games that are already multiplat anyway.

If they did that, then there would be absolutely not point in me owning a 360.

PS3 would give me literally everything I would need.

twest explained it pretty well already though, trust in him.