Download latest version (1.0), released 2008/12/05.
The idea is that you can just update the version number in your theme, and browsers will automatically get the latest copy rather than keeping their previously cached version of the stylesheet.
The latest version of this plugin has been tested in WP (and WPMU) 2.6.x. It will probably work in older versions as well, but your mileage may vary.
Please post any questions / comments on the current release page for this plugin.