Microsoft's Interoperability Principles and IE8

"We've decided that IE8 will, by default, interpret web content in the
most standards compliant way it can. This decision is a change from what
we've posted previously [about IE8 and 'Quirks mode']. Basically, all
the browsers have a "Quirks" mode, and use it to offer compatibility
with pages that pre-date modern standards. All browsers have a "Standards"
mode, call it "Standards mode," and use it to offer a browser's best
implementation of web standards. Each version of each browser has its
own Standards mode, because each version of each browser improves on its
web standards support. There's Safari 3's Standards mode, Firefox 2's
Standards mode, IE6's Standards mode, and IE7's Standards mode, and
they're all different. We want to make IE8's Standards mode much, much
better than IE7's Standards mode... Our initial thinking for IE8 involved
showing pages requesting "Standards" mode in an IE7's "Standards" mode,
and requiring developers to ask for IE8's actual "Standards" mode
separately. We made this decision, informed by discussions with some
leading web experts, with compatibility at the top of mind. In light of
the [Microsoft] Interoperability Principles, as well as feedback from
the community, we're choosing differently. Now, IE8 will show pages
requesting "Standards" mode in IE8's Standards mode. Developers who want
their pages shown using IE8's "IE7 Standards mode" will need to request
that explicitly, using the HTTP header/meta tag approach. Ray Ozzie,
Microsoft chief software architect: "We have decided to give top priority
to support for these new Web standards. In keeping with the commitment
we made in our Interoperability Principles of being even more transparent
in how we support standards in our products, we will work with content
publishers to ensure they fully understand the steps we are taking and
will encourage them to use this beta period to update their sites to
transition to the more current Web standards supported by IE8..." More InformationSee also the announcement: Click Here