I had this problem myself and made a quick fix.
Open plugins/wp-polls/poll-js.js and use a JS beautifier (like in TextMate) to uncompress it and change line 17 from:
jQuery("#polls_form_" + poll_id + " :checkbox, #polls_form_" + poll_id + " :radio").each(function(b) {
to:
jQuery("#polls_form_" + poll_id + " input[type=checkbox], #polls_form_" + poll_id + " input[type=radio]").each(function(b) {
I may not be 100% accurate, but to try and explain… the problem occurs due to Cufon using VML to render text, which in IE only has certain attributes associated to each tag. If a script, in this case, jQuery, tries to check one of these invalid attributes, IE will throw an error. It usually always comes down to checking type, which I believe doesn’t exist for vml:image or vml:group.
