Thank Goodness. In a rather surprising move, CATSA annouced carry-on luggage would be re-allowed on US-bound flights from Canada from January 20th. In addition to one carry-on bag (not to exceed 40cmx55cmx20cm), U.S.-bound passengers may also bring a purse, diaper bag, laptop, or camera bag. Books, iPods and medicine must be stored in the carry-on bag.
Here's a link to a video refresher on what's allowed on carry-ons and in what quantities.