What size are you looking for and what features? I second the Islabikes recommendation--we have the 20" Beinn small for our daughter and it's great. It weighs in a 17.6 lbs stock, but we've added the fenders, rack and panniers. We are expecting our Cleary Bikes 16" Hedgehog for our son tomorrow, so I'll be able to give a firsthand review of that shortly.
Since you're in Canada, definitely check out Spawn Cycles. The Furi and Banshee are very lightweight. Also, the Opus Nix and Doppler are both under 10 kg.
At the less expensive end of the spectrum (since there's a widespread re-sale market), the Specialized Hot Rock bikes are comparatively light, particularly in the 12" and 16" sizes. The 20" geared bike isn't that much lighter than the competition.