I've just moved to Canada and brought my (legally) unlocked iPhone from Australia with me. I have a two year working visa here.
Rogers were unhelpful, and said a) they could not let my phone on the network, and b) they could offer me a new iPhone with a three year contract (despite my insistence I'd only be here for two at most, legally).
Fido (a Rogers company, of course) were more helpful, offering a month-to-month plan (i.e. no contract) with relatively acceptable rates and allowed me to use my device on the network. Fido++
I avoided any contract at all, though, because there's strong rumour that Bell and Telus are launching a combined GSM network sometime this month (or next) so they can cash in on the iPhone and try and get some roaming dollars when people arrive for the Winter Olympics next year. So competition is soon to arrive, and Canada's mobile telephony options should be much more interesting soon!