Hi,
we did a test with a GPRS upgraded Treo and several providers. Its interesting that whenever you change the SIM card of a provider, the Treo automatically has the new GPRS settings for the new service.

We did tests with T-Mobile Germany (T-D1), vodafone D2 and O2 Germany.

Just change the SIM card, turn on the wireless unit and *voila* just go online with GPRS with no additional settings.

Think thats cool.
-markus