C'è di più, anche IE può far vedere i bordi arrotondati ma è decisamente più complicato: nel css
codice:
/* IE */
	behavior:url(border-radius.htc);
il file border-radius.htc
codice:
--Do not remove this if you are using--
Auther : Remiz Rahnas
Auther URL : http://www.htmlremix.com
Published date : 2008/09/24
<public:attach event="oncontentready" onevent="oncontentready('v08vnSVo78t4JfjH')" />
<script type="text/javascript">
function oncontentready(classID) {
  if (!this.className.match(classID)) {
    if (!document.namespaces.v) {
      document.namespaces.add("v", "urn:schemas-microsoft-com:vml");
    }
    this.className = this.className.concat(' ', classID);
    var arcSize = Math.min(parseInt(this.currentStyle['-moz-border-radius'] ||
                                    this.currentStyle['moz-border-radius'] ||
                                    this.currentStyle['border-radius']) /
                           Math.min(this.offsetWidth, this.offsetHeight), 1);
    var strokeColor = this.currentStyle.borderColor; var strokeWeight = this.currentStyle.borderWidth; this.style.border = 'none';
    var fillColor = this.currentStyle.backgroundColor; var fillSrc = this.currentStyle.backgroundImage.replace(/^url\("(.+)"\)$/, '$1'); this.style.background = 'transparent';
    var margin = this.currentStyle.margin; this.style.margin = '0';
    var styleFloat = this.currentStyle.styleFloat; this.style.styleFloat = 'none';
    var clear = this.currentStyle.clear; this.style.clear = 'none';
    var position = this.currentStyle.position; this.style.position = 'static';
    var left = this.currentStyle.left; this.style.left = '0';
    var right = this.currentStyle.right; this.style.right = '0';
    var top = this.currentStyle.top; this.style.top = '0';
    var bottom = this.currentStyle.bottom; this.style.bottom = '0';
    var width = this.currentStyle.width; this.style.width = '100%';
    var height = this.currentStyle.height; this.style.height = '100%';
    this.outerHTML = '<div class="' + classID + '" style="background: transparent; border: none; padding: 0; margin: ' + margin + '; float: ' + styleFloat + '; clear: ' + clear + '; position: ' + position + '; left: ' + left + '; right: ' + right + '; top: ' + top + '; bottom: ' + bottom + '; width: ' + width + '; height: ' + height + ';"><v:roundrect arcsize="' + arcSize + '" strokecolor="' + strokeColor + '" strokeweight="' + strokeWeight + '" style="behavior: url(#default#VML); display: inline-block; width: 99%; height: 99%; antialias: true; padding: ' + strokeWeight + 'px;"><v:fill color="' + fillColor + '" src="' + fillSrc + '" type="tile" style="behavior: url(#default#VML);" />' + this.outerHTML + '</v:roundrect></div>';
  }
}
</script>
Per ora è così e basta, poi un domani si vedrà.