So if the market share report links below are in the ballpark, that is about 60% of IE's current 49% market share, or about 29% of all current browsers. This makes jquery 2 a non-starter. Even using 1.9 is suspect because the questionable decision making process here makes me think I will have more headaches in the future if I stick with jQuery.
IE Market Share: http://bit.ly/LUhxlA
IE Version Market Share: http://bit.ly/LUh9n2