The peeps at Nclud came up with a revision to the clearfix method of clearing floats.

.clear {
  display:inline-block; /* or anything that triggers hasLayout in IE */
}
.clear:after {
  clear:both;
  display:block;
  content: ".";
  height:0;
  visibility:hidden;
}

Valid CSS 2.1 and a bit cleaner than the current clearfix method.