Not to mention it doesn't need to impede on your current activity. Currently, if you're doing some work in an app, you can either close the app, create the reminder, go back to your app and try to get your brain back into the mindset of using that app. OR, you tell yourself that you'll create the reminder when you've finished completing the process you're doing in the current app (in which case you might forget to create the reminder altogether). I think Siri will help a lot in performing actions in the mobile/tablet space where multitasking is just not as simple as the desktop.
I always wished I had the android style "stack" of applications on my iphone for just this reason: short one-off tasks. But I also knew apple would never do it. This seems to be the solution they are going to push.
