It would appear that Microsoft had second doubts about their unwillingness to adopt Standards Compliancy in their forth-coming IE8 browser. On their IE Blog the new announcement apparently follows Microsoft’s new Interoperability Principles;
"We’ve decided that IE8 will, by default, interpret web content in the most standards compliant way it can."
Wired.com were inclined to think otherwise and instead the reason may have just as well been due to "the widespread criticism from the design community — condemning IE 8 for not defaulting to standards mode — coupled with lawsuits from the likes of Opera and the EU, played a large part in the decision."
No matter the real reason behind the new decision to enable the Standards Compliant mode as the default option. It will mean that Web Designers can at last hope for an IE browser that renders their web sites in similar or identical fashion to Firefox, Safari and other modern browsers which have been compliant all along.
In the long run It should mean a faster development cycle and more time spent on designing sites as opposed to writing alternative stylesheets to fix bugs and quirks in IE.
Remember that the end user of a well designed and functional web-site is the one who really benefits here.