Congrats to DrHowardDrFine and everybody else that kicked up a stink. If that blog post is carried through, it looks like IE8 will do standards first and compatibility modes second.
Imagine that! It's a Good
Imagine that! It's a Good Thing® that MSFT is taking a long view of the issue and has made the correct decision.
As long as IE8's quirks mode rendering is ≈IE6's, I don't think the disruption will be all that bad. Sites written against standards mode in IE6 or IE7 are likely under continuing maintenance and revision will come fairly easily. The cost of change will only rise with time. The sooner the changeover the cheaper for all concerned.
I've never seen so much positive response to an IE blog article. The only negatives seem to be from MSFT fanboys.