Get Real
There's a lot of whining idiots on here who don't seem to get what is going on.
For the first time, Microsoft are embracing the standards and promising full support for them in their browser. Whether this is because they are losing market share to firefox, or because it is the right thing to do is another matter, but frankly, who cares? The outcome is the same - good for everyone.
All these people going on about 'I will make my site to the standards and IE can f-off if it doesn't like it' is all well and good, but try telling that to a client, who expects their website to work in the most popular browser. In short: Get real. Get out of cloud cuckoo land where everything is perfect and noone cares that your site breaks in IE, because at least you are standards compliant la la la... - it just doesn't happen. Get a grip!
While the original plan for this tag was terrible (where IE8 defaulted to IE7 mode), the change to make IE8 standards compliant by default is fantastic. This tag is a PERFECT way to ensure a smooth changeover, and I'll be adding it to all my sites straight away. This way, I can remove it in a testing environment when IE8 comes out, and make sure there are no problems with IE8 in my own time, rather than rushing to sort it all out when the browser is released. Is this not an ideal solution to the usual problems of a new browser version? I will be adding it to my sites straight away, even though they are all 100% standards compliant, because... well, you never know what can happen with a new release. I would say it is pretty irresponsible not to do so.
I'm pretty fed up with the whole 'everything MS do is evil' thing as well. Yes, IE5/5.5/6 were terrible browsers, but go before that - IE4 pioneered the use of CSS in web pages (admittedly only to get one over on Netscrape, but still) and the competition was poor. So they have lagged behind a bit (lot) in recent years, but now they are trying to make amends and all people seem to be able to do is whine about it again. It seems whatever microsoft do, everyone think's is 'evil' or 'wrong'.
And yes, IE8 Beta 1 sucked. Probably because it's a beta. The clue is in the name...