Open Data

I'm at OSCON06, where Tim O'Reilly has been talking about the concept of open data, which is much easier to explain versus open standards and interfaces. You should be able to use an application (open or proprietary) and pull you data out and walk away. Now a number of vendors like to lock their customers into their products so that the switching costs are very high.
But I think that if you really tried to implement open data some customers would be more willing to buy a proprietary product if they know they can walk way at any point.