Projects like bit.ly or su.pr or tinyurl.com are more and more popular there days. Big companies like Google (goo.gl), Facebook or Microsoft are creating their own.
Today, people use them on the internet, because its a easy way how to share links between people. They also provide some statistics, who clicked on those links.
I predict they will be hugely used in mobile marketing. Because SMS can be only 160 characters long, here is really a scarcity on characters.
SMS are one of the best ways how to get mobile website to target consumer, these short URLs will be placed in those messages.
In additional, there are really some cool stuff you can do with them in SMS from analytic perspective.