i would like ie9 to have VS2010 like MEF plugin model, so we get more sorts of plugins from the community.
bookmark sync (or mite be create some standard open api's)
download manager that can pause and resume (and if others want, must be allowed to install other download managers)
installation of multiple versions of IE. especially for devs to test.

and might have a licenese agreement where, MS has the right to upgrade the browser via windows update automatically once its too old like IE6.