Not only is it shorter, the new name is more literally communicative of what the service does. Click on it and you will J.mp [jump] to a new link. It's nice and literal like the old classic tinyURL, though most people don't know what URLs are. J.mp is so friendly it makes Bit.ly look like a way to catch a bit-delivered virus. J.mp might be the best URL shortener name yet. How do those Bit.ly guys do it?
J.mp was first discovered by Dan Frommer at Business Insider hours before the official announcement and the announcement was retweeted by super news-hunter Atul Arora in under 3 minutes after it went live. Now we've given it just a few moments' thought and posted this account less than 15 minutes after the news was official - the Bit.ly blog displays the age of its posts in minutes.
Such is the nature of the super-fast, perhaps Real Time, social web that Bit.ly is a big part of.
You can visit J.mp and get all the same bookmarklets and tools for the new URL that you've got for Bit.ly (the "sidebar" tool is excellent). We expect that leading Twitter clients like Tweetdeck and Seesmic will likely add J.mp support soon. We wonder if Twitter.com will stop transforming long links into Bit.ly links automatically (a deal that was announced this Spring) and will use J.mp instead.
In case you're curious - .mp comes from the Mariana Islands, which are just South of Japan.
There are a number of efforts in the market to create community-owned URL shorteners, with features serving developers first before the interests of private owners. Most notable among them so far is Tr.im. It would be a shame if enthusiasm for such projects was lost over one fewer letter being taken up by J.mp. That said, this new URL J.mp will likely be just the latest development from a company that's building itself into a strong market leader.