What I continue to find funny in your post and in many posts that I'm reading while going through this thread is that people keep saying "noise-cancellation, noise-cancellation, noise-cancellation." You people continue to assume that users are directly in mid traffic downtown New York City 24 hours a day and couldn't possibly use Siri when they're at home quietly especially if they wish to dictate something instead of type.
What is also hillarious is that I use my iPhone 4S while its in my pocket with Beats earbuds that have a noise-cancellation mic so why couldn't someone use headphones with noise-cancellation to bypass this "issue" that seems to be so persistent in being the main reason why Siri isn't on iPad 2? iPad 2 has a similar processor and similar RAM so that shouldn't be an issue either.
The only reason why Siri isn't on iPad 2 is because Apple continues to make "features" specific for certain products so they nickle and dime their consumers for a product that isn't as superior as it is and could be come 6 months until the next release of their "new but not so new once the next model comes out new iPad."
I'm giving up with Apple products now that I've noticed that all Android devices get almost all the features it can get even if it is a year or few months old and even if you do have to wait a while for the phone manufaturer to test and release the update. Planning to UPGRADE to Galaxy S3 in a week.