Free software programmers are fond of saying that they'd prefer not to reinvent the wheel. Apparently that attitude no longer applies to desktop menus, considering all the new options springing up.
A few years ago, just about the only menu choices on the main desktop environments were the ones that shipped with them, or the exhaustive Debian ones. For five years, GNOME didn't even have a menu editor. However, recent years have seen an outbreak of experimentation, ranging from Windows-inspired menus such as openSUSE's default Slab, the Vista Menu for GNOME Panel (which seems to have taken up where the apparently defunct USlab port to Ubuntu stopped), and the menu in the newly released KDE 4, to menus whose goal is to integrate social networking into the desktop, such as BigBoard and Gimmie. Apparently, the old style accordion menu is no longer functional or fashionable enough.