When I did a yum updated which installed numerous packages including a new kernel (2.6.12-1.1456_FC4), it hung after installing the kernel-devel package. I waited a few minutes, and pressed CTRL+C at which point it gave me the following error: error: %post(kernel-devel-2.6.12-1.1456_FC4.i686) scriptlet failed, exit status 0 Stupidly, I didn't try it again but yum update worked fine after I removed the installed kernel-devel packages. Trying to install it on its own afterwards succeeded.
whilst it seems like it 'hung', it was probably running hardlink against any other kernel-devel packages you had installed. The more you have, the longer it takes.
Fair enough, I did have about 8 installed... :)