Links with a 'rel' attribute like "rel='address:test'" will be found and prepared by jQuery Address' function $.fn.address. One of the things it does is add the 'submit' event through the $.fn.live function. jQuery actually adds a 'click.specialSubmit' event (on line 3237), a function that checks the 'type' attribute of the clicked element.
In our case we have a link that's prepared by jQuery Address and Cufon. When we click on a Cufon VML object inside the link (thus on a letter), jQuery's 'click.specialSubmit' function is invoked on this element, this function checks the 'type' attribute and makes Internet Explorer 7 en 8 alert an error.
Click in MSIE7/8 on a Cufon'd letter!
Extensively discussed at: sitecrafting.com/blog/jquery-cufon-dont-mix/,
Reported to Sizzle: github.com/jquery/sizzle/issues/17,
Reported to jQuery: bugs.jquery.com/ticket/9807,
jQuery v1.6.2 source: code.jquery.com/jquery-1.6.2.js