Remind me: why do we need short urls at all, rather than a better solution? Removing arbitrary limits (or better impl. thereof) seems betterI guess Leigh's talking about the need for short URLs in tweets, but I wonder about the more general question of why we need URL shorteners at all. Reading the Guardian (physical copy in a coffee shop) I keep coming across URLs in the text, such as bit.ly/seth52, that is short, no "http://" prefix, and labelled in a human readable form (the short URL's in Seth Finkelstein's column are all of the form bit.ly/seth[n]).
It occurs to me that these URLs are almost like tags, the names have locally significant meaning, and are memorable. In a sense the URL shortening service acts as a new namespace. Imagine if you can't get a desired domain name, but can get a customised URL with that name. The tyranny of the DNS as the sole naming authority is weakened a little. In some ways this mirrors how many people use the web. Instead of typing in full domain names, they enter a search term into Google and go to the site they want (often the top hit). Imagine if Google provided a URL shortening service (in a sense their search engine is a slightly clunky one already).
The other reasons I'm interested in this is because of ugly identifiers such as urn:lsid:zoobank.org:act:6FFAFC2C-D46B-4959-BA03-C38477B9DFF1. This version, bit.ly/polina is a bit nicer. Plus, I get usage statistics on the short version (meaning I don't need to implement this myself). If we use the Guardian as an example, perhaps journal publishers using LSIDs such as urn:lsid:zoobank.org:act:6FFAFC2C-D46B-4959-BA03-C38477B9DFF1 would prefer to use custom, shortened URLs to make the text more readable, and collect usage statistics as well.