Vodafone announced a pre-paid data access plan earlier this week – one of the first of it's kind I believe that does not force the subscriber to commit to monthly payments or annual subscriptions. I like this idea. Adoption of EV-DO, 1xRTT, etc. cards has been in the low single digits as a percentage of wireless subscribers. Our data show that a small percentage of mobile professionals are "frequent travelers" defined as at least weekly business trips. One would typically need to be a frequent traveler to justify $60 to $80 per month in data access fees. Per usage (on a byte meter) charges gives the carrier a more direct means of competing with hotspot services, opens up the market to a larger audience, and provides a better means for employees to bill their employers for travel expenses.
The service does seem to be on the expensive side – I, at least, would not use the service to download a lot of music, photos or video at more than 3 British pounds per Mbyte (and more than 9 British pounds when roaming internationally). It does offer an alternative though.