UPDATE: Replaced files with Axure 5.6 compatible versions
OpenExhibits.org has a large set of gesture icons available for download (free). Here are the one and two finger gestures in Axure widget library format (.rplib). Stay tuned for more.
Download the Two Finger Gesture Library
Illustrations provided by Gestureworks (www.gestureworks.com)
Another good Axure gesture library can be found on conetrees.com