Question: Recently there has been a lot of hype about URL Shortening. I guess some URL Shortening services even offer tracking stats. But, doesn't adding one more level of look-up to the original URL affect page ranking in any way? Just curious to know.

Answer: 
Well, I can tell you one thing that *won't* affect your PageRank - URL shorteners using DNS.

The vast majority of URL shorteners use clientside redirection - either via scripting/meta-refresh, or via frames. Those might affect your ranking as they change what Google sees - you never know. Examples are anything from [Dot.tk](http://dot.tk) to [PopNIC](http://www.popnic.com/), [Smartdots](http://smartdots.com), [JoyNIC](http://www.joynic.com/), [HomeNIC](http://www.homenic.com/), [EuropNIC](http://www.europnic.com), [Tipdots](http://www.tipdots.com), [DuoNIC](http://duonic.com), [UnoNIC](http://www.unonic.com/), [Cydots](http://www.cydots.com/), [FreeNIC](http://freenic.at), [Mediadots](http://mediadots.com), [Ulimit](http://ulimit.com), [kurzURL](http://kurzurl.de), [co.nr](http://co.nr) and [de.be](http://nic.de.be)/[de.vu](http://nic.de.vu)/[ch.vu](http://nic.ch.vu).

A few services are using proper DNS for forwarding, though. Those include [Afraid.org](http://afraid.org), [co.cc](http://www.co.cc/), [No-ip](http://no-ip.com) and [Da.ru](http://da.ru). This is fully transparent to visitors and spiders, so you can be sure it doesn't affect your rank.
The criticisms of URL shortening have reached near hysteria. Combine this with SEO guidance that borders on superstition if not outright voodoo and you'll find a lot of (mis)information out there. [URL shortening is a storm in a teacup](http://www.cforcoding.com/2009/06/hysteria-over-url-shortening.html). Don't expect it to make any difference to search engines.