The author of the review, Brett Terpstra, summed up tagging in the following way:
The tagging concept, to summarize, basically allows a file to exist in many collections at once, as opposed to being stuck in one folder. Tagging can be used in combination with a folder hierarchy, or allow for flat storage and organization through search mechanisms. Tags allows you to classify not just files, but also web pages, iPhoto images, Address Book entries ... just about anything which would need to be collected to organize a project.I have taken to tagging my photos as soon as I load them in from my digital camera. The success of the method, as with any organizational scheme, is to actually use it. After using the system for a couple of months I found it much easier to find a specific photo using a few key words. I bought a little shareware program called Keyword Assistant a few years back to help me out. It made it much easier to tag my photos. Tags (the program) looks to make it convenient to tag all my files?
I had my first set of web kids crash and burn this week because of unorganized files. Their links were failing and they couldn't even find the files they were linking to. They didn't like me very much when I told them they had to get those files named and organized before I'd help them troubleshoot. I refuse to deal with a group of files all named "untitled".
Every gray hair on my head has at it's root an untitled.html file. (Sorry....I just had to say it!)
[Image captured from TUAW article: Tags takes organization to a new level:http://www.tuaw.com/2009/01/19/tags-takes-organization-to-a-new-level/]