Mac App Store,
Apple has learned a lot from their 'iPhone App Store' they've been going about with it for 4 Years now, and nobody has been able to come close to that.
They've in a way redesigned this whole App business on mobile phones, Can u imagine the state of Mobile apps before that ? It used to consume whole lotta time searching for Symbian apps , and in the end u wouldn't know if this 'App is compatible with your phone, Or 'Will it end up breaking your phone' or 'How would you know (painlessly) if the newer versions of that particular App were introduced.
Now they want to apply those learnings to their Mac , and they are not wrong about it, Remember most of the people who Own an iPhone also own a Mac, and those who own an iPhone know how to use the 'App Store' and have been doing that for years now they love its 'App Management, App Discovery, App Updation' etc , Instead of searching for apps on Blue hyperlinks and Static pages, what they see here is all sort of apps aligned in a beautiful interface, with reviews, One click 'Download-Buy-Install' , Automatic updates, Auto-Save and resume etc, Its a killer IMO, this is what App store should be, or atleast should have been to BEGIN WITH.
MultiTouch,
iPhone introduced the first ever True MultiTouch experience and potential to the world, It was an instant killer and cyanide to the Stylus/Other touch phones, Wether it was Playing games , browsing internet or cruising through Photos or many other apps, MultiTouch was MEANT to be. Now MultiTouch does exist in current generations of OSX but , the OS itself is not designed to enjoy the full potential of that,
Now we still don't know how MultiTouch will help in improving the UserExperience when it comes to doing Emails, Office work or anything similar, but we can surely think it will complement the Multimedia/Entertainment department and also to the UI of the OS itself, We all know that it would be a delight and pure eye candy to cruise quickly through a collection of photos, or Maybe like a Flick of 2 fingers would bring up the newly introduced 'Mission Control' or maybe a 'MultiTouch Guesture based shortcuts/Commands' and ofcourse any of the 'Touch, Swipe, Flick, Tap' can be used in many ways to complement OSX Lion in general.
Its quite possible that OSX Lion would turn out to be the OS that people are most excited about and are waiting eagerly for it.