Well, here's a nice surprise. The Nexus 4 has a working LTE radio in it! We just confirmed it working on the TELUS LTE network. Check out the above video for the how-to on enabling LTE on your Nexus 4.
TELUS has the same band 4 LTE (1700/2100MHz) as Bell and Rogers, so you can use Nexus 4's LTE on those networks as well.
UPDATE: Check out our Nexus 4 review!