They are, but times vary between the iOS vs. the Mac App Store. I recently submitted a new app to the Mac App Store and it took about one week to get initially approved (with one rejection because I had the word "Mac" in the app description (they said it's redundant since they're all Mac apps anyway...). Could've been a quick regex check in the form submission, but anyway, after the initial approval any subsequent feature submission afterwards usually got approved within 2-3 hours, same day, which is pretty good IMHO.