What can I do with X11?
There are plenty of apps available for X11. Most distributions of Linux, BSD, Debian, Sun or other flavours of Unix contain many apps that run in the X11 environment. By creating an X11 client for OS X, Apple has made it easy to port these apps from Unix.
Another advantage of X11 is that you can connect to a Unix-based server via ssh, and call up programs on that machine. The GUI will be redirected to the client, so that you are running a remote program but it seems like it is running locally. I do this at university a lot as we have specialist Sun servers running the Sun CDE desktop environment, and I am able to use these machines from my Mac.
Finally, there are a handful of great desktop environments, or "window managers", for X11. Among my faves are Gnome, KDE and Enlightenment.
I just wanted some sugessions on getting started with X11. Where can I get X11 apps and where should I start with this thing. I am very interested on learning more about this.
The mac program Fink will help make it easy to download and compile binaries from SourceForge along with all the needed tweaks to get them to run on a PPC.
If you're not afraid of compiling your own software, you can get the X11 SDK from Apple's developer site. I wouldn't know where to start with this, myself.
A lot of the software on X11 is extremely specialised toward medical, engineering or programming applications.
Worthwhile apps are the open-source Office alternative OpenOffice, or Sun's StarOffice (which is based on OpenOffice). Gimp, an image editor with filters, actions and tools that compare nicely with PhotoShop, though aimed more at multimedia than print graphics.
If i were to install KDE with this X11 would I get a desktop in a window?
The X11 Server runs in "Rootless" mode, which means that X windows appear on the Mac desktop alongside Mac programs. They look like Aqua windows, they minimise into the Dock, like aqua windows, and they behave almost like aqua windows ... though with a few odd quirks since each X-Window app is like a document within a program, much like if you had a few browser windows open, they are kind of grouped together when you switch.