In my last post, I picked on The Trouble With Tagging - and when you consider tagging in the context of content, you run into the trouble of navigation. Content Management Systems permit tags to be used as a way to find similarly tagged content. This is in the hope that the content itself will be similar simply because it's tagged the same, but that's not necessarily true.
If we consider it in the context of real world 3D navigation - something I know something about - using tags as they are presently popularly lused - we're taking a single data point and extrapolating where we are. While it's true that you need to know where you are to know what's around you, the reality is that it's just not a great way to navigate content.
In the days when Second Life popularity was at it's peak, 3 dimensional navigation of content was so interesting that Amazon.com spent some money exploring the idea of navigating products in 3 dimensions. That didn't work out too well, though intuitively it made some sense. The trouble was that the finding of a book in a bookstore, while charming to some of us, is not what made Amazon into the powerhouse it is. The foundation of Amazon was being able to allow people to find what they wanted quickly and purchase it quickly - allowing those lucrative spontaneous purchases where we consumers don't have time to think about whether we should actually spend the money.
I watched in Second Life as Amazon.com did their R&D, and came to a conclusion before their project ended: Nothing they could do in a virtual world could measure up to what they had done in a 2D world (your browser) simply because they had taken multidimensional navigation to a new level.
While much of the Internet was busy selling their goods, Amazon.com was finding ways to connect things through navigation that were working. That's why Amazon.com is still standing and many people who were late to the game remain unknown.
There Are Still Issues
Consider what I wrote in Online Shopping User Experience vs. Design. It remains flawed because not everyone sees the world the same way, and because we use nouns and adjectives as single points to navigate by.
The future will likely be using more than one point to navigate by. It works for use everywhere else but on the Internet.