Clicking on a program's button in the task bar does not always bring the app to the foreground. This seems to be the case when Netscape is covering the window in question. This is functionality that is critical to usability. KDE handels this correctly.
Verify that you have upgraded to the latest GNOME RPMs that are available on the updates site. Reopen this bug if you continue to have trouble after updating.
i haven't found any GNOME RPM's in the updates site. I did find an enlightenment update at http://niteowl.userfriendly.net/linux/RPM that fixed this problem for me.