Can't visit css3pie.com with IE6 ?!
I am trying PIE and have tested it through a Windows XP/IE6 VM (delivered by Microsoft) here
and by visiting your site, but get a 503 (Service Temporarily Unavaible).
I have verified that is not a network issue on my side.
Tested it after discovering that IE8 (Windows 7 x64) don't display any gradient or round corner (when visiting your site again).
Not tested with IE7 and IE9.