I do agree the whole registration issue is weird and quite possibly typically American. Everyone over 18 should be registered automatically by virtue of being alive. In Australia prior to each election volunteers throughout the country go door to door to check everyone is registered correctly, providing all the necessary info/forms to fix any issues on the spot.
(I'm learning a lot about the American electoral systems in the Coursera Digital Democracy course. America definitely has enfranchisement problems in some areas.)
Anyway, back on topic: boot time signatures is something I'm definitely watching. We sometimes have to place machines in untrusted environments and it would be really nice to be able to ensure that no-one can boot the system from any other media.