In the mashup ecosystem, let’s get one thing straight. The data owner is ultimately in control, because a mashup developer is reliant on data owners to keep the supply of data flowing.
Sure the presentation is important, but if you rely on data sources you don’t have control over you run the risk of losing out. Better to get permission from your sources before you are blocked from getting the data. One should never base your business model on free data unless you have secured access to it.