There, I said it. Siri really is amazing. People who think it is just voice recognition software need to try it before passing judgement. This is BETA according to Apple, learning a trick from Google. That just means they are going to tweak it with user data. Some of these things are not working (yet):

It does not work with third party app. "Play Norah Jones" only work if you have her music on your music library. We need it to work with Rdio or Spotify, like Dragon Go does.
It does not take multiple calendars into account. I have 25 appointments next week according to "check my schedule", what I really want is "check my work schedule"
You would think you can send tweets from siri, with all the twitter integration, but you cannot. You can say "text twitter" if you have twitter setup as an account with code 40404, the standard twitter SMS interface. You will be using your SMS credits though.
It will be nice if it interface with either the calculator app or something more streamlined for basic calculation, and then read back the result instead of showing me a wolfram alpha page.