I would not want to be in Twitter's shoes right now. Google has taken Twitter's follow model and seamlessly integrated it into Google+. But Google+ seems to offer everything Twitter offers and much, much more. With Google+ you can broadcast to your hordes of followers, just as with Twitter, but you are no longer limited to 140 characters. You are also no longer limited to characters alone!That misses the fact that the success of Twitter is driven by brevity. The 140 character limit means that I can quickly scan a list of tweets for things that look interesting. And the limit forces the tweeter to pare down what they have to say to 'just the facts, Ma'am'.
As Blaise Pascal (or was it George Bernard Shaw or Mark Twain? The web isn't sure) wrote: "I'm sorry this letter is so long, I didn't have time to make it shorter." Twitter forces users to make tweets interesting in 140 characters or be unfollowed.
Google+ may have the 'follower' model that Twitter does but it looks more like an RSS feed than a tweet stream. Here for comparison is the visible portion of my Twitter feed and my Google+.
Strunk and White expressed this well in 1918:
Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts. This requires not that the writer make all his sentences short, or that he avoid all detail and treat his subjects only in outline, but that every word tell.And every other style guide (AP, Chicago Manual of Style, etc.), not to mention the advice of writers like George Orwell, points to combing brevity and clarity.
Successful tweeters know that and write accordingly.