Here's to hoping someone eventually develops a way around this. I'm waiting on delivery at this point and, quite honestly, won't use the device if my phone can't be jailbroken.
Same here. I wasn't aware of this restriction.
Edit: actually, they don't say it can't be used on a jailbroken phone. It's just not supported. This is from their site:
Running Square on a “jailbroken” phone or mobile device with a modified operating system is not supported.
To me, that means that it will work, but if data is stolen or a user runs into problems with Square on a jailbroken device, Square is not obligated to help.