Standard behaviour

I used to get really excited about the release of new versions of the big web browsers. These days the overwhelming emotion is worry, bordering on panic. What is it going to do with the HTML I lovingly crafted to work with its predecessor?
I held my breath this morning as I fired up the first beta version of Internet Explorer v8 for the first time. And whilst there’s nothing catastrophic to report, I’m surprised how may things are ‘a few pixels out’, even things you never thought could be risky. If you’re reading this on the puffbox.com site in IE8, for example, you’ll see the ‘find’ button is out of line with the search box, and there’s an unexpected gap between the header and navigation strip. The Wales Office site adds a few (inactive?) horizontal scrollbars to various DIVs.
There’s been a lot of talk about Microsoft’s Damascene conversion to web standards: effectively they’re saying ‘no really, this time we mean it.’ And Ray Ozzie appears to be thinking and talking long-term:

On one hand, there are literally billions of Web pages designed to render on previous browser versions, including many sites that are no longer actively managed. On the other hand, there is a concrete benefit to Web designers if all vendors give priority to interoperability around commonly accepted standards as they evolve. After weighing these very legitimate concerns, we have decided to give top priority to support for these new Web standards.

In other words, standards-compliance over legacy support. That’s the message web designers want to hear. As I’ve written before, I’m convinced the bulk of HTML coding effort is spent making the same design work identically across all browsers. An across-the-board commitment to universal standards would end that waste of our time, and clients’ money.
So why am I looking at pages which are fine in Firefox, fine in Opera, fine in Safari, fine in Konqueror… but a bit off in the new standards-compliant, ACID2-passing IE8? (No browser hacks, before anyone asks.) Please, please, let this just be ‘a beta thing’.