I tried his button styles on submit and button inputs. His basic "button" style and the various color and shape variations still work great and degraded well when I checked in IE7.

You can view the results here: http://www.webcodeshare.com/agx3ZWJjb2Rlc2hhcmVyDwsSB1dlYmNv...

Only a small addition was needed to turn off left and right borders.