Twitter has officially launched their Tweet Button - a natural move which will place them beside Facebook's like buttons... and across millions of pages on the web (soon to be on this blog!). The question is what happens to everything else? There is only so much space on each page and ultimately publishers will only devote real estate to those buttons that deliver the most traffic / engagement. Twitter and Facebook will clearly qualify - but who else? My favorite example is this post from Mashable which leaked the Tweet Button a couple days ago. The Tweet Button screenshot sits below the Facebook Like graph and beside Tweetmeme, Digg, and Facebook Share. Of course there are others: For instance, I use Apture and Disqus. And more will come - like Facebook's long rumored social bar.