Is it just me, or is the somewhat robotic voiceover demoed on Siri a bit underwhelming? Try to compare it to the Nuance supplied voices for Lion (downloadable), such as Samantha for US English. The latter is far more natural sounding, and while it comes at a certain cost in terms of size, wouldn't it be worth it? Nitpicking, I know, but the voiceover is basically the same as is already part of iOS, and that one has never been particularly nice.