There have been lots of articles from tech pundits over the last month talking about the potential of Siri and how google should be afraid of losing their search stranglehold. And I think they are right. Siri will expand to the iPad and Mac. Siri will gain lots more funcionality, hopefully including developer API's. But one thing I think that Siri will really need in the coming future to become a powerhouse is an optional text input (and output) in addition to voice. There are hundreds of situations I can imagine where text is better. While watching TV, while having a conversation, while a child is sleeping, while in a club, etc etc... Then google will become the default in these situations unless the OS is prominantly built around an immediate access to Siri with text input. I think voice only input is a great start, especially on the iPhone. But for Siri to be successful on the iPad and Mac, I really think text is more appropriate.