Why are all of those Emu programmers not working together ? I think it would not be to hard for all to work together and make a working Emu faster and easyer.

Is it because all those Developers want all fame only for themself or how comes ?

depends on what emulation scene you're talking about. everyone in the NES scene works together and documents as much as possible and shares information openly. MAME is open source for the arcade emulation community. lots of things are open source. i'm not too sure what you mean?

Given that this is a post in the Dualis forum, I'm pretty sure he means DS emulators.

As for why they aren't collaborating, there could be many reasons.

#1: Programming languages
#2: Programming style
#3: Doing this is a personal goal, want to work alone
#4: Haven't considered the idea of collaborating
#5: Liscencing issues (One emulator may use a liscence that isn't compatible with another, and may incorporate code from something else making it impossible to change the liscening agreement)

Only the authors know, hopefully they may answer your question themselves.

Yeah I am talking about NDS Emulation...

I didn't think about that they use diffrent programming languages.. but the other points i don't realy understand...

Hopefully there will be anything working...

P.S isn't it possible to combine diffrent programming languages ?

Yes, but not WITHIN the same source. For example emulator A has it's ARM9 core written in ASM, and emulator B has it's ARM9 written in C.......this is a huge hurdle.
But if emulator A has it's GUI written in ASM, you could bring that over into emulator B and replace emulator B's C GUI with it. This all provided the source is clean and seperate for each piece (Which is how most programmers work), it would require modification....but far less than trying to combine a complete ASM project with a complete C project.
That would require a lot of rewriting. I don't know what languages each respective emulator is programmed in, my interest in the DS is minimal.

I'd say this is the key point for me. But we do share information among the authors - we just have different ways of implementing things.