Why everyone is interested in URL shorteners?

First it was Twitter, now it is Google Facebook and also YouTube. 

All have started using URL shortening services. But why does this sudden move to change from long URLs to really short ones?

It seems all are interested in tracking. Hootsuite is a perfect example. It shows number of clicks for shorten URLs. This is true for various services like TweetMeme.

Google uses this for tracking feeds using Socialize service in FeedBurner. 

References:


Mashable