[erroneus]

The problem of running Linux on things is getting the specific hardware functions to work at least as well as the original maker's software does. Once basic functionality has been established (which is the most difficult part) then any variety of Linux apps can be recompiled and tweaked for the new environment. (It would need to be since attempting to run X.org and GNOME would be a ridiculous idea... the UI should be better suited to the existing hardware.)

And again, once that huge hurdle of gaining acceptable functionality is achieved, things like syncing and email and other fun apps become instantly open for development and exploitation, unlocking all the power of the devices often kept hidden or restricted for a price by the phone service provider.