To expound a bit on Michael's post: the nightly builds are (strangely, I know) generally more stable and hugely more feature-rich than RC2. (Though some people have been complaining about crashes on Linux recently, I haven't ever had issues myself; I use Mandriva.)
In any case, you'll find that the majority of RPMs don't make any visible changes to your desktop or menus. Rather, they bury a few files in the bowels of your filesystem and it's up to you to know about 'em. In Code::Blocks' case, the 'codeblocks' executable is installed to /usr/local/bin, and you can execute it by entering 'codeblocks' at a shell prompt (if /usr/local/bin is in your $PATH), or creating a symlink to it on your desktop, or what have you.