Just when those bit.ly URL’s started to look like they were getting just a little too long, Bit.ly introduces j.mp.
As far as we know, everything works precisely the same as before but we’re trying things out ourselves as we speak, so we’ll keep you informed.
In May, Twitter switched to bit.ly from TinyURL as its built-in short URL service, and usage exploded. With that explosion comes lengthier URLs, so it makes sense that the service would cleverly introduce alternative shorter URLs.
At the moment, the two sites appear as though they were completely different services, albeit designed identically, but you can visit j.mp and login with your bit.ly credentials as normal. You can also add the j.mp bookmarklet and use that URL exclusively.