If you're in a contract with a carrier, I'd suggest phoning them up and asking to speak with their retentions department. Talk to them about how you're thinking about leaving if you can't get an iPhone 4 soon. Most of the big carriers -- Rogers, Telus, Bell, and even Fido -- have taken orders through their retentions department. It really seems to depend on the day though, whether or not they can sell any. But it's worth a shot!