The iPhone and iPod Touch applications store from Apple has been a gigantic success.  Much like McDonalds, the App Store has 1.5 billion served and counting in a year.  Granted, not all of these have been paid applications and most of them have been free and/or updates, but that’s an impressive number given the relatively small number of iPhones and iPod Touches in the marketplace.

Of course, eventually, the leader in the software industry would have to get involved in this game too.  Enter Microsoft and Windows Marketplace, with their staggering 30 million-ish install base of smart phones running Windows Mobile.  True to form, while Apple leans on games, MS is going to pin its hopes on its massive business base with a separate business section of the Marketplace featuring names familiar to the enterprise user.

I know only a few people who use smart phones or PDAs that don’t use something BlackBerry or Symbian related.  Then again, Microsoft and Apple are newly entering the phone business and have the marketing capital and cultural cachet in their audience of business folks and hipsters to elbow their way to the top eventually.  Their aggressive strategy of opening up app stores will definitely help their cause.

Do you have a smartphone now?  What sort of features might cause you to chuck your current piece of technology for something sparkly and new from Apple or Microsoft?  What’s *your* killer app?