bit.ly why? how?

Have you ever thought about bit.ly ? What is their business model? They just shrink urls, right?
Not exactly ...
Its gives you much more. Link live stats , posting to twitter ...
Take a look at this link.
But isn't weird connection between twitter and bit.ly? It is made perfectly for twitter who have limit in max number of characters and they have common investors Betaworks. Well, sort of cause BetaWorks sold Summarize to Twiter for $15m and twitter stock options. Silicon valley is very small place, guess I have to make a post on all relations between VC, startups and contracts between them. Like, usage of bitly small links on Twitter is not by chance, a lot of other API/tech deals in Valley are driven by VCs and their interests.