I think this is up to the service provider(aka Carrier). For example, Telus Canada here seems be preparing to push service books for BB 9900 hot spot. But I think this is highly customizable by the service provider. What that means is, even if you get wifi hotspot features, your service provider can add restrictions like, maximum number of unit can get wifi (most likely 1 device), network timeout(how long you can use it straight), how much data you can get in an month through wifi hotspot, etc, etc.
Anyway, I am not sure either... It is still a mystery. We need Sherlock Holmes to do some dig in to RIM and their service provider partners.
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