AFAIK Nokia will be using the Microsoft App Hub/Marketplace for its WP 7 phones. Now there is a huge "problem" with App-Hub for non-US developers: the tax registration process. If you read through different WP 7 related discussion boards you see dozens of complaints from non-US developers because the tax process is really cumbersome (smallest errors lead to problems with forms; the whole process is unclear). Although MS staff tries to help, the problem has not been aleviated in the past.
With Nokia joining the WP 7 community, will there be a simplification of this process? For an european publisher providing a simple VAT (resp. higher taxes for individuals without a VAT id) should be sufficient...