TPM is not only about locking down the user. Trusted computing means reducing the trusted part to
really be able to observe and analyse it, and thus be really trustful.
It can be really useful when on the hand of the user (or a company), you can rely on it for your own
secure operations.
In Maemo6 case, though, the private key is not on the user hand, which means he can't really use it
for himself, as it seems.