Due to Windows 7 release, many people indirectly upgrade from IE6 -> IE8 these days. You can see this here and here.
With IE7, IE8, FF, Chrome, Safari & Opera - the web would look much better. PPK's forecast -Â that adding IE6 support would cost more money to the business - is becoming real.
This basically means that web is getting more standard than it used to, and "sites the work only in IE" should become rare even in the short term. Amen.
(Also, these days IE8 is starting to overcome IE7)