This morning Twitter users found themselves unable to navigate to any links that were shortened by Twitter's own URL shortening service. AllThingsD reported that the company had no comment on the issue, and Twitter's status blog had no information on the outage either.
At one point in the morning, Twitter switched over to the URL shortening service Bit.ly, which fixed the situation temporarily. At the time of this writing, the service has been restored to Twitter's in-house URL shortener and several test confirm that everything is back to normal and working fine.
We just noticed an issue with our link to our Twitter account from TweakTown, which doesn't work with the trailing slash in the URL, whereas it did before this morning. We're not sure what happened to Twitter, but we'll report back if details come to hand.