When the race is for being short how companies can stay away from investing money behind it. We know competition of url shorten services. To beat tinyurl.com , bit.ly is doing so hard work. And when the competition is for getting short own main domain length matters.
To decrease the domain by 2 characters bit.ly started their new service m.jp, which is also same url shorten service like bit.ly . Difference is just length of the domain.
You can use your bit.ly account to login in j.mp .
Hope tinyurl will introduce something very nice to give tough competition.