rev="canonical" and url shortening
Maybe I'm completely missing the point, but even the "alternative shorter" proposal seems a bit idiotic to me. I'd like to take a step back and try to figure out what problem exactly we're trying to solve.
Why do we need to make our url's shorter?
Url's should be meaningful. We use url's very often, so being able to spot what a certain url is likely going to link to is very helpful. If, for some reason, creating a meaningful url is difficult, you definitely want to make sure the urls stay under a certain amount of characters. Long, bulky urls might be broken apart into multiple lines in emails and cause other usability issues.
Services like tinyurl fix that problem. It doesn't solve the issue really well though. These types of services introduce (well documented) privacy concerns and break the address bar.
"The worst problem is that shortening services add another layer of indirection to an already creaky system. A regular hyperlink implicates a browser, its DNS resolver, the publisher's DNS server, and the publisher's website. With a shortening service, you're adding something that acts like a third DNS resolver, except one that is assembled out of unvetted PHP and MySQL, without the benevolent oversight of luminaries like Dan Kaminsky and St. Postel."
Sadly, services like tinyurl has become immensely popular due to the rise of Twitter. Twitter has a 140 character limit on messages, and many urls can actually be more than that.
'Short urls' do not solve a technical problem. The extra few bytes and characters are negligible. The only true problem rev="canonical" solves, is the fact that page owners do not like the fact that their urls are hidden behind an obscure 3rd party service, and rightfully so! People just started caring because their uptake is rising.
Instead of spending time on trying to figure out how to solve this problem on the url shortening service's end, we should try to help twitters VARCHAR(140) into, well.. a TEXT field? Am I going overboard here?
All sarcasm aside, there are definitely ways twitter can keep the actual message size down and store urls separate from the actual 'tweet'. And as developers, we should boycut url shortening services for everything other than tricking people to watch video's of Rick Astley.
Don't even get me started about the Diggbar, or Facebook's recent link framing. Next time you try to up your Alexa rating and ad revenue, please try to focus on developing a business model that spans beyond 1 decade, instead of screwing tons of small businesses and independent authors that provide their content for free.