We've already talked about Square, the app/dongle/website combo that turns your iPhone into a mobile credit card payment device. But talking is one thing: seeing it in action is another. And that's what Jack Dorsey (Square co-founder and Twitter creator) does in the above advertisement. Granted, an ad's primary function is to sell you something, but the video actually succeeds in making the Square system look easy, foolproof, and — dare we say it? — fun to use.
Right now, there are no real mobile transaction solutions in the US (although Verifone and Morphie are readying similar solutions even as we speak). Market properly, Square could do for smartphones what PayPal did for the Web: create a user-friendly way to accept credit card payments that EVERYONE wants to use.