Here's a bit of a long-winded explanation, but the short answer is, unless you want to listen to the repeater inputs, you shouldn't notice any issues.
The "700 MHz band" runs from 763 MHz to 806 MHz, much like the "800 MHz band" runs from 806 MHz to 824 MHz (for inputs) and 851 MHz to 869 MHz (for outputs). Both the 700 and 800 MHz bands have standardized input offsets, as does the lower UHF portion of the RF spectrum (400 MHz - example, the input for 413.x is standardized as +5 MHz, so 418.x).
The inputs for the 800 MHz band is -45 MHz, so 851.0125's input is 806.0125. The input for the 700 MHz band is +30 MHz, so 763.00625's input would be 793.00625.
It remains to be seen if Canada is going to treat the 700 MHz band the same way the US is, but if they do (and from the licenses it looks like it is probable), frequencies from 763 to 768.99875 (and thus also 793 to 798.99875) will be used for conventional non-trunking purposes. Trunking takes place between 769 and 775.99875 (and the inputs on 799 to 805.99875).
For reasons not explained publicly, GRE scanners (and the scanners they make for Radio Shack etc, since they are just GREs with a different case) seem to have a problem between 796.x and 806 MHz in that they receive images, or unwanted duplicates of signals elsewhere in the RF spectrum. In GRE's case, the radios receive images from the 800 MHz band into the 796-806 range. It's not as simple as a straight mathematical link, i.e. 796.8125 does not equal 866.8125, but it's in that neighborhood. I have personally seen this in Lethbridge (there's a thread in this forum about it) with my PSR500 and PSR800, and others have experienced the same behavior in plenty of other places all over North America.
This is a problem in the GRE's hardware, not in the software/firmware. The solution GRE has put forth to date involves preventing you from being able to tune in to that section of the 700 MHz band. If you have a newer GRE scanner, or a GRE scanner with a recently applied firmware update, odds are you will get an "out of band" error (or it will tune to 796.0 or 806.0, depending on what end of the "blocked band" you are trying to enter) if you try to key in a frequency in this blocked portion of the band.
This problem cannot be fixed with a firmware update. The problem presumably lies in the circuitry of the receiver and would require physical changes to fix it. GRE is coming out with a PSR-900 very soon which appears to be a base/mobile version of the PSR-800, and I don't know if that portion of the band has been opened up in that radio. There is a "pre-release thread" somewhere in the GRE forum on RR that may have that answer.
The good news is unless you make a habit of listening to the input frequencies (portable/mobile radio to the trunk system tower), this shouldn't affect you. I fully expect all trunk system frequencies will fall between 769.0 MHz and 775.99875 MHz - and so far that is the case in the licenses and live sites that have been discovered.
One last comment about the PSR-800 though - for a system such as this which is still being discovered, the PSR-800 may not be the ideal radio. Its design is more centered around taking things from the RR library (filtered through GRE's servers) and loading them in to the scanner. While it is possible to create custom systems using GRE's Ez-Scan software and load it into the 800, you can not do any "on the fly" programming, i.e. if you are out and about and want to add a new trunk site, unless you brought your computer along with the software and cable, you're out of luck.
Having said that, I regularly carry around the PSR-800 along with a PSR-500, and a 396XT and have an HP1 mounted in the car. The next time I have a reliable signal for a tower site and there is some voice traffic, I will try each of them to make sure they can track the system. I know the HP1 will do just fine, so I am pretty confident any modern Uniden will work. (I also have a 996T, PSR-600, and another HP1 at home, and when the signals reach that area, I can try it on them too.) Once I confirm which scanners can and can't track the signals, that information will become part of the Wiki article.
Naturally scanners that do not do the 700 MHz band (my old 796D is one such animal) will not cut the mustard. Also, I have no confirmation of this yet, but I believe the VHF portions of the system will be "One Freq Trunk" (in Uniden's terms) systems, but we'll see.