Now, if your hands are like mine this is a pretty big deal as it will make a whole bunch of the iPad's functionality much more accessible.
So far I've been very impressed with the iPad threes voice to text functionality, but it's limited in its accessibility. Basically the way it works right now is anywhere you have access to the keyboard, you have access to the voice dictation function. Siri however will allow you to all sorts of things simply by pressing the home button such as create e-mail, reminder, search for something on the web, etc.
Is a video of what Siri can doon the iPhone 4S… Hopefully all this functionality will be available to the iPad. This is some great news! I can't wait!