Firefox 3, which hasn't been released yet, is gaining a significant following, and has just overtaken Opera Software's Opera 9 desktop browser in global market share (according to Net Applications.) I wonder if Firefox 3 will be able to break 1% global share before it's even released. That would be pretty crazy.
With millions of people already using the pre-releases of Firefox 3 and the enthusiasm around the arrival of the final release, I have no doubt that we'll see Firefox well above 20% global market share in the very near term.