TechCrunch asks if url shorteners are evil.
URL shorteners are just lossless information compressors. Much like a zip function compresses information, in the same way URL shorteners compress a URL. No information is lost, but we need more resources to decompress and use it than in the original state.
There is one big difference between a function like zip and a URL shortener: the first one is based on an algorithm, all you need to extract the original information from a zipped file is knowing the zip algorithm. On the other hand, URL shorteners are using dictionaries: each URL shortening service is a dictionary that translates the short URL back to the original. If we don't have access to this dictionary, the compressed information is useless.
In a way, there is a power shift from many to few: what everyone could read and "understand", (ie go to a URL), now needs someone else's permission, or at least existanse, to be read (ie the service must be up and running to convert the short URL to its original form). I think that's what bothering Dave Winer when he says that "We need to prepare for the day when N of the URL shorteners go out of business. When that happens a large part of the web will die. It will not be a good day."
Obviously, URL shorteners are useful, that's why they exist. They are useful in cases where we are willing to sacrifice some resources (CPU cycles, and a couple extra HTTP requests) to have the same information consume less space (characters in this case). What us users should be asking for is a piece of the "power" we lost. "Let me map my own domain onto theirs, easily back up all my data, and give me the ability to switch services when I want, or when I need to", says Winer.
But that's not all. Many URL shorteners go beyond information compression. They keep extra stats, like click stats. They capture user "gestures" and user "attention". They let us know "how many users clicked on the link I suggested on twitter", when they did, etc. Marketeers have been using intermediate URLs for years to measure email and banner effectiveness. Many URL shorteners give this feature to everyone.
Unfortunately, these intermediate URLs (in the form of short URLs) are the best tool we have to do this right now. This is why I don't see URL shorteners going away, even if we found an algorithmic (and not dictionary-based) compression method to shorten URLs. But there's an interesting field for new tools there.