Apple made this concept famous with the App Store for the iPhone, as of January 6, 2011 - there is now one for Mac OS X!

took a quick breeze - pretty painless - I like it - the fact that it tracks versions for you is a nice feature in itself

Apple's Mac App Store fundamentally changes PC software usage rights - game changer indeed - you purchase an app once and you can download it to any device you want. which means if you surf your friend's couch often, you might as well make a login on his/her mac and download all your apps. assuming you're putting your files on something like Dropbox - you may not have to carry your macbook ever again. but then again, the iPad has gotten a head start here :)