Good news for the developers – IE8 will pass Acid2, a test case, written to help browser vendors ensure proper support for web standards.
Microsoft has put a lot of effort in IE development to comply with the standards, a proof of which Acid2 compliance undoubtedly is.
Please also note that it has not been easy for Microsoft to achieve. Due to all kinds of flaws and incompatible rendering in previous versions, any sudden move towards standards-compliant engine may break millions of sites and webware that depend on a specific version of IE. So it's really a balancing between backwards compatibility (legacy rendering) and standards compliance.
For the compromise IE8 introduces a new feature – META tag to specify a version of IE. So basically we are talking of a version targeting:
or in a bit more advanced form considering other brands as well:
and finally, targeting the latest version of IE:
Even though it's a very nice enhancement it's likely to remain IE-based, again. All the other major browsers on the market have been respecting standards for quite some time already, namely Opera, Safari and Firefox. So there's no sites breaking over legacy rendering on these platforms which is exactly why WebKit (the team that does Safari framework) has basically denied the above feature.
In contrast to the release of IE7 Safari 3 didn't break any sites built for Safari 2.