I just rented two SIMs from SoftBank last week, for a G1 and iphone. I kept the iphone hidden because I knew that wouldn't fly, and just lied my face off and said the G1 had no smartphone capabilities.

They were not happy with the fact that I could not produce the second phone because not only do they check to make sure the SIM is working, they make you both send and receive a call to their phone to really make sure. I forget exactly what their data charges are (I think it was 0.32 a packet) but it was exorbitant.

In general I have found they are not willing to rent to you if you have an iphone, and they are also not willing to rent to you if you cannot produce the phone.

Last time I used Telecom Square because they don't have data capabilities but this time they said they no longer rent SIMs.