Microsoft has reversed its decision to make IE8 behave like IE7 unless specifically requested and will interpret web content in the most standards compliant way by default.

Background
Microsoft were to use a new site versioning feature in IE8; a meta tag which would be used to define which version of the IE rendering engine should be used:

<meta http-equiv="X-UA-Compatible" content="IE=8" />

This caused an outrage in standards groups because this statement stated IE7′s rendering engine would be used by default. This meant that IE7s poor rendering engine would be used unless the above meta tag was included in your web page.

Now Microsoft have done a U-turn and have stated;

There is a concrete benefit to Web designers if all vendors give priority to interoperability around commonly accepted standards as they evolve

It seems Microsoft have taken on what the developer community have been saying / shouting which is a complete turn around compared to their usual strategy to ignore. Even there long term goals are now going in the right direction

Long term, we believe this is the right thing for the web. Shorter term, leading up not just to IE8’s release but broader IE8 adoption, this choice creates a clear call to action to site developers to make sure their web content works well in IE.

Hopefully this new strategy will filter down to other Microsoft products and a standardisation harmony will follow ..

You can read more in the following press release entitled Microsoft’s Interoperability Principles and IE8 and more on the reason for the change – Microsoft Expands Support for Web Standards