Apple is currently in a bit of a pickle. Twitter is deeply integrated in the OS (both Mac and iOS). It makes sense that they invest a few days worth of profit to secure a more formal partnership.
I'm not sure why, at least at this point — it seems like it'd be really weird for Twitter to turn off the ability to post statuses/photos/etc and have an OS-wide account sign-in feature, which is basically all Apple's OS integration does. Like, so weird that you'd think Twitter would probably be making themselves irrelevant, so you wouldn't really care anyway.
