IE's browser share is about to dip below the 30% mark
Unfortunately is is still holding it's own in N. America @ just under 40%. http://gs.statcounter.com/#browser-na-monthly-201112-201212
But IE 9 has been eclipsed by Chrome in N America http://gs.statcounter.com/#browser_version-na-monthly-201112-201212
And why does this matter? IE is an anchor browser and defines the lowest common denominator of what technology you can use client side with out writing conditional code for IE. Even the latest and greatest IE 10 (Win 8 only) still lags behind in HTML5 support.
And IE 8 and 9 still suck ass big time.
This said, FF and Chrome's 6 week release cycle and auto update starts to make a LOT of sense. Things are moving FAST and the traditional 18 month release cycle just cannot keep up with the pace of technology on the web.