I\'ve never seen
The fact that I have never noticed
The hash "#" currently works for jump links in conjunction with the base element, but only in the latest versions of Google Chrome and Firefox, NOT IE9.
IE9 appears to cause the page to be reloaded, without jumping anywhere. If you are using jump links on the outside of an iframe, while directing the frame to load the jump links on a separate page within the frame, you will instead get a second copy of the jump link page loaded inside the frame.