Here in Oklahoma it doesn't get cold enough to use a block heater. Sometimes I think that it would help, but then my engine jumps up and heats up quickly.
Cobb, I don't think the block heater would help you too much anyway (with a hybrid).
HotRodEconomist, looks good. Not too sure how much it would help down in Texas, but it should help a little, as long as it doesn't heat up the engine so much that the radiator fans start turning and causing drag on the alternator.
__________________
|