I'm surprised at the amount of people on LWN who concentrate on just the what-the-user-gets-now instead of the benefits of actual freedom of usage instead of vendor lock-in. We're not really talking about what the user gets now even when talking about Linux booting on the iPhone.
opensource takes off once a produce becomes 'useable' and people start using and improving it.
until something hits the 'usable' threshold it's only used by tinkerers.
exactly what the 'usable' threshold is varies from person to person, but most people will not be willing to put up with significant problems for the tools that they need to use to do their real work.
nowdays a cell phone is a critial tool, the requirements for stability and reliability are extremely high.
closed source phones 'just work' (as phones anyway, they may have headaches for other uses), and Apple has done a good job of making the iphone 'just work' for many of the other uses as well.
openmoko has lots of neat features, but in the 'just works as a phone' category, it's still lacking (although another poster said that the 'next release' is expected to fix many of these problems). as such it's not a realistic choice for anyone who actually needs a phone for daily use.