T-Mobile HotSpot has been coy in the past about what they charged: Email from the company today to hotspot subscribers points to a page that fully lays out what you pay when you connect to each of their partners.
T-Mobile Europe is a whopping 18 cents per minute or over $10 an hour, in contrast to T-Mobile USA's $6.00 per hour pay-as-you-go rate. It's also odd because T-Mobile UK, for instance, charges just £5.00 per hour, which is about US$9.00.
Domestic US airports are a better deal, though, as T-Mobile has a negotiated rate of $4.99 per day (per location) with its three airport partners (Concourse, Cingular, and Opti-Fi), which is several dollars less than the walk-up price for single day sessions.
Any explanation for why T-Mobile Europe is much more expensive? This does not help their brand at all! If you are a T-Mobile customer in the US and then you try to use their service in Europe, you will feel totally ripped off.