In the upcoming release of iOS 6, Siri will be undergoing a number of changes. One of the most significant is the integration of third party apps such as Yelp and OpenTable.
Features include being able to find a place to eat and getting average prices, Yelp reviews and more. Rotten Tomatoes integration is seen when you ask about movies, and you can launch trailers from Siri. You can also launch apps with Siri.
Another feature is Eyes Free, where Apple is working with automakers to include a Siri button in the steering wheel so it can be launched without having to mess with the phone.
The biggest feature is that Siri will be coming to the third-generation iPad. Sadly, the original iPad and iPad 2 will not gain Siri capability.