This rules applies to IE7, but not IE5 or IE6. It also applies to most other browsers, and all of the ones that matter - all except older Konqueror builds (3.0 or earlier), Netscape 4, and Opera 5.
#test1 { co\lor /**/:green; }
This text will be green if the rule has been applied
So for general use, if IE7 can be treated as a "good" browser, the following pair will differentiate that group from older versions of IE:
/* IE5 - IE6 */
* html element { property:rule; }
/* IE7 and other modern browsers */
element { pro\perty /**/:rule; }