I had wondered if you could just get your own MiFi and do a SIM only deal with them. You can get Euro MiFis off Amazon.com. They will work in the US as well, but the frequencies offered are better for non-north American usage.

One of the other posters is correct that we glazed over the Blackberry issue. Blackberries really need a Blackberry plan for data usage. You can use some over wifi but you need an active Blackberry account to go through to get the data. Also, my old Blackberry 9000 would not connect to ad hoc wifi networks which limited my ability to share my data with it.

If you got the 64.99 ATT Global Blackberry account, you might be able to sneak some tethering in with either the Tether or PDAnet programs. The problem is that your iPad can't tether with the device, only your notebook.