This link, http://www.microsoft.com/sql/editions/sqlmobile/howtobuy.mspx, explains how the pricing models relate to Sql Mobile. While it is somewhat ambiguous in my mind, my take away is that if you are using the server plus user model, you do have to pay for each device running Sql Mobile that will touch a real Sql database, however if you are using the processor model, about 25k per proc, then there is no additional cost. Hopefully if this is not correct someone from MS can correct.