First off, this tip does not work with all menu bar items, only Apple-provided menu bar items (like the clock, WiFi status, iChat, etc.) and select third-party application menu bar addons. This reason behind this how to do with how developers add an item to the menu bar: only items through OS X’s SystemUIServer will work with this tip. 

Dragging the WiFi status Menu Bar item.

Back when I first switched to the Mac, I couldn’t for figure out a way to move the items on my Mac’s menu bar around. The only way I could figure a way to do it was to manually enable/disable them in the order I wanted them to be displayed. This tip is a simple solution to that problem.

The Tip: Hold down the Command key and drag an item around on the menu bar. If you drag an item off the menu bar, that item will disappear with the same “poof” as icons dragged from the dock. Items that are moved around will remember their locations after you log out or restart OS X.

Spotlight seems to be exempt from this, it cannot be moved or removed using this method. Also, many third-party allocations that have menu bar items do not work with this tip.