Extremely awesome. My only (nitpicky) objection: I wasn't able to do a simple

  $('#myProgressKnob').attr('value', _new_value_);

and have the graph around the edges update. The number in the center changes, but the circular part doesn't get updated (at least, for me). I really wanted to use this in my latest project (shameless plug: http://wwikt-peterldowns.dotcloud.com) but couldn't make it happen so I'm switching back over to the twitter bootstrap progress bars in the meantime.

Disclaimer: I'm a totally new to JS and could be trying to do something un-possible. Thoughts? Has anyone else been able to make this happen?