This page demonstrates the memory leakage problem as it exists in Internet Explorer. Open up your task manager and look at the memory usage of the browser you're using to view this page. Then hit refresh repeatedly to see the memory usage increase.
The JavaScript creates 500 closures which contain references to just the body tag. On my system I've seen memory increases of 500 - 600 kB's in IE. Firefox handles the test without any leaks. Opera shows a more unsteady memory usage curve, but overall the memory usage hardly increases.
You can also check out this script with some code to prevent the memory from leaking.