T 10k is a dev. software used to compile for the PS2 architecture.
The way PS2 games are developed are with a licensed compiler from Sony that allows code to be executed on the PS2 architecture. Kind of like if you write a program in C++ for a PC with API calls you have to change the API calls and recompile it for Mac. Same thing with Console systems.
The tools they use are their own tool kits. They use dev. kits that most companies have developed for the genre of games they are creating. Like Bungie uses various kits and dev. enviroments to create objects for Halo instead of constantly coding the same objects over and over. Some kits you can look at that are free or very cheap are Torque and Crystal Space. (I think that's what its called)
Overall you can find a dev. enviroment for PS2 but you will also need the loader software that is loaded at a certain sector on every PS2 disk which allows the data to be loaded into memory of the PS2 and the game to begin executing. The "Linus Enviroment" is along the same lines as the HomeBrew kits for PsP. It allows an interface with the PSP or PS2 architecture to simulate a different enviroment so you can code as if your were writing a game for Linux. That is simply all there is to it. Then the Ps2 will run the linux enviroment and games on the hard drive but this is hardly hard core PS2 game dev. as I said before you will need a PS2 compiler, the API calls, and the boot program to burn to the cd/dvd. (By the way, the boot program is NOT free as this is how many people have "hacked" games and burned themselves.) Programming games on any console system is learning a different architecture to program to. They have similarities with modern PC's but realize their processors are much lighter weight while the GPU's are a lot heavier in comparison to PC's, allowing for MUCH higher graphics qualities.
I hope this explains a bit more on top of what Nova has said.