I think this is another "make the platform better" move more than anything else. My biggest gripe with every new app is the "Sign in to Twitter to share" button and off late I have stopped doing that. This feature now lets developers use a simpler API to allow sharing while removing the hassle to end users. Again this is one of the features I love in Android where any application just sends a "share" intent and other installed apps can respond to it, allowing app content to be sharable beyond the services the developer could have imagined.