So, the LG Nexus 4 has a dormant LTE capability inside, and no it's not going to magically start working with LTE. Or is it? Kind of, is possibly the best way to describe what we're now starting to see. Seems some enterprising types up in Canada have been fiddling with things and amazingly have managed to kick LTE into gear on TELUS and Rogers by changing a setting in Android's testing menu (*#*#4636#*#* in the dialer app).
It all stems from an apparent compatibility with LTE band 4 on the 1700MHz and 2100MHz frequencies, due to the existing radio assembly supporting LTE on those bands. It looks like for some reason LG decided to leave a fully functional LTE radio on the N4, but disable it through a software setting. In Canada, LTE band 4 is supported by TELUS, Rogers and Bell. Outside of Canada, your HSPA+ Nexus 4 won't be able to pick up any LTE reception, unless you're in one of the very few markets AT&T has enabled LTE on band 4.
It's a neat trick, make no mistake, but before we all go running off to try and do this we should remember a few things. Just because it's possible, doesn't mean we'll be able to make good use of it for a number of reasons. Firstly, it's no use anywhere outside of Canada right now. Secondly, the Nexus 4 is not approved for use with LTE anywhere in the world at this moment in time, and as such it will likely be patched out in the future to avoid LG getting into hot water with the regulators. Remember, the Nexus 4 is marketed as a HSPA+ phone for a reason, and regulations have a part to play in that. Technically, it's unlawful to use LTE on these bands without regulatory approval, even if all it takes to enable it is a quick setting change. (It's also slightly baffling as to why LG would've left LTE radio software in a non-LTE phone -- presumably this is a hang-over from the Optimus G rather than something specifically designed for the N4.)
In any case, click on past the break for a walkthrough video of how it all came about.