How can you force a stylesheet reload in Drupal7?

Question

This is about that old trick of tacking a fake query argument onto the URL of a stylesheet (e.g., <link rel="stylesheet" type="text/css" href="http://www.example.com/site.css?v=123">) so that, when you change the stylesheet, it'll be reloaded by the users' browsers, since it looks like a URL that's not in the browser's cache.

So, the question: How can you do this in D7 where the stylesheets are specified in the .info files? I tried adding a query arg onto the entry in my site's info file -- stylesheets[all][] = site.css?v=123 but without any luck (the page rendering got very unhappy). Any ideas?