Another option if you travel frequently to Canada and foresee this issue arising again is the new "passport card":
http://www.state.gov/r/pa/prs/ps/2006/74083.htm
http://www.flyertalk.com/forum/showthread.php?p=9064051

This would be valid for purposes of the Western Hemisphere Travel Initiative, i.e. travel to Canada, Mexico, and the Caribbean, and would be like an "extra" passport in credit-card-like form, without room for stamps or visas.

I kind of doubt you can get one of these in the coming week in Canada, but who knows.... If you could get one on an urgent basis, you could use it to re-enter the US and mail in your booklet-style passport.