Array() doesn't seem to be called when defining an array with [] in Chrome 12 and Firefox 3.6+
It obviously worked this way at some point (http://news.ycombinator.com/item?id=2668888), so I'm guessing the older IEs, at least, still have this flaw.
In Firefox 4 and other new browsers this is no longer the case. But right now it's still an issue as many people are using older browsers.