Read about this in the Rockable Press "Building Wordpress Themes from Scratch" book, he quotes Dan Cederholm on this and I think it's a great idea:
So for developing WP themes we need to have some pretty generic class naming, so we want the following:
To ensure that these classes don't do anything they aren't supposed to, like extend past where they should let's clear them, but let's take a different approach.
So if we used these in our code it would look something like this:
<div id="mainContainer" class="group">
<div class="left">Left-floated Class</div>
<div class="right">RIght-floated Class</div>
Instead of using the empty div clearing, or even clear-fix this mainContainer div will clear after itself. But what about older browsers that don't like the whole pseudo-class selector? Of course we have a fix!
* html .group{ /* This fixes is up IE6 if you still support it */
*:first-child+html .group{ /* This is the IE7 fix */
Self-Clearing floats! I can't tell you how happy I was to find this little trick since I am what you might call a "div floater". To learn more about self-clearing floats, head on over to http://handcraftedcss.com