If you want to test Pan between releases, you can download it from Gnome's SVN repository.
live.gnome.org has instructions
for getting it.
"pan2" is the module name for the rewrite that went public in April 2006.
"pan" is the module name for the older, unmaintained version.
If all goes well, runnning "./autogen.sh; make" in the pan2 directory will
result in the executable pan2/pan/gui/pan.
Compiling Pan requires the header files for gtk2, pcre, and gmime.
On most systems these are optional packages named gtk2-devel, pcre-devel, and gmime-devel.
You'll need one more optional package, gnome-common.
Remaining tools typically come built-in on systems configured for development:
gcc, m4, automake, autoconf, pkg-config, and intltool.