I kept bumping into this thread while I was searching for shortened url's for a Dropbox Showcase. In case anyone else like me is looking for that kind of shortened url (to share a Showcase), I finally found it myself. You click Share at the top of your created Showcase. It brings up a dialog box that at the top allows you to put in an email address. At the very bottom of that dialog, it has an option to Edit link. Once you click on that, you can shorten up your showcase name and replace the long unreadable string with a readable string. Just thought I'd post this solution here because I kept bumping into this thread as I was searching for Showcase url shortening. Hope this helps someone.
... View more