[blub]

The web app already has all my data on a server somewhere. And that web app is 99% of the time closed source. And the company can cut me off, change the TOS or sell my info to advertisers. Now THAT's a lockin.

While you identified the problem, the solution is a truly open mobile OS, not webapps.

[javajosh]

How does a truly open mobile OS (and applications, presumably) solve the problem of vendor-specific data lock-in? Data lock-in is a totally separate, and far more difficult, problem. Part of the reason is that our data a) probably wouldn't exist, and b) probably doesn't make sense out of the context of being mixed together with everyone else's data. There is a strong a priori centralizing force for some important kinds of data.