Scott Rose notes that there is a slight inconsistency in the way that Mac OS X 10.3.x handles cycling through applications (using the Command-Tab keyboard combination) when the user invokes application hiding:
"There is a bug in the program switching capability of Panther (when you hit command-tab to cycle thru applications). If you hit command-tab to cycle to the most recently used application, and then you hit HIDE that application (by pressing command-H), that application no longer shows up next when you hit command-tab again. It's as if the program switcher FORGOT that you just came out of that application. The normal behavior is when you hit command-tab twice in a row it cycles you back & forth between your 2 most recent applications. but if you hide one of the apps in between there, that app is incorrectly removed from the cycling order."