Hmmm...
Trent Canal system, Lake Simcoe, and Severn River should all be fine thru-out for cell coverage. You may find some WiFi along this route. There are areas in Georgian Bay in small craft route that cell coverage can be spotty as you head further north. Entering (descending into) Georgian Bay at the locks at Port Severn, north up to Parry Sound, is my home area, cell signal fairly reliable, but can disappear when you venture deeper into some anchorages and bays. I have not ventured to the Benjamin Islands, or The North Channel, so maybe others have experience with cell signal there.
IMHO, there will be no WiFi to speak of, generally. I use my iPhone4 for internet when necessary, it can also create a 3G hotspot for my laptop if needed.
Major cell carriers here are Rogers, Bell, and Telus. I use Telus, my wife Rogers. They may have a pay as you go cell arrangement that would suit? As Canadians, we're used to overpaying for cellphone coverage/plans, IMO!
There's an interesting WiFi thread on 'Ask the Captain'. Not sure if the products/antennaes mentioned can be used succesfully here, but would like to know myself. Over-air HD tv, internet and enhanced cell signal is on my list for this year.
