The following piece of PHP code was appended on top of my index.php file, from my WordPress 3.0 distribution:

if (eregi("MSIE",getenv("HTTP_USER_AGENT")) ||
eregi("Internet Explorer",getenv("HTTP_USER_AGENT"))) {
echo $msie_warning;
// exit;
}

The variable $msie_warning holds the HTML code for the following warning, which displays on top of all pages to viewers who send MSIE or Internet Explorer in their browser signatures:

You are running Microsoft Internet Explorer, which is unsafe and will negatively affect your browsing experience. Please use another browser to visit this site, thanks!

The original code simply blocks Microsoft Internet Explorer users, as shown by the commented exit; line, but I could not resolve myself to be that coercive. However, I do target all versions of the browser, even when they support the Google Font API and render pages almost correctly.