Motorola appears ready to take on the Slingbox and Sony's LocationFree TV with a new service that allows customers to stream television from a DVR to a cellphone. However, there are some caveats that may make the service little more than a novelty for the time being. The biggest limitation for the moment is that the service will require both a Motorola DVR and a next-gen RAZR phone. Since Moto's DVRs are built into set-top boxes provided by cable companies, and not sold directly to consumers, this means the potential user base is defined not by customer choice, but by the vagaries of the cable market. And, of course, you need a specific phone model -- one that doesn't currently exist on the market -- to make the service work as well. However, given that the service is just in demo mode at this point, a lot can change before it goes public. And Moto may well learn from Sony's experience with LocationFree that it's better to open up, rather than trying to force customers to stick with a closed system.