Updates:
Status: Invalid
Comment #1 on issue 1201 by pekka.klarck: IEDriver executable needs to be
available in the path
http://code.google.com/p/robotframework/issues/detail?id=1201
It seems that newer Selenium 2 versions use different approach to communicate with IE than earlier. Just follow the instructions and you should be fine.
Notice also that this is Robot Framework issue tracker and Selenium2Library has a tracker of its own. In this tracker issues related to Se2Lib are invalid.
