Tagging and Folksonomies...Useful?

If I've gone on a big day or night out with my friends and taken lots of photos, the first thing I will do when I return is upload them to Facebook and tag all my friends in them. By doing this my photos will now appear on their pages, and all my other Facebook 'friends' can see who I was out this. Until now it's safe to say I've never actually thought about what I was doing, I've always just done it. This photo is an example of how easy it is to tag someone in a photo or even a comment on Facebook.

But I think the idea of the lecture was to look at how we find information, tagging enables us to do this. For example on search engines such as Google all we really need to do is type in one key word, and a whole range of search results will show up. This links me to the word 'Meta-Data,' which is basically a key word which is typed into a search engine such as Google or Yahoo and will give you all results linked with your word.
So, tagging like Meta-Data,

allows a user to add categories to different things.


http://www.spicynodes.org/blog/2010/09/13/thomas-vander-wal-when-folksonomies-transplant-taxonomies/?gclid=CJrNl63Z9LYCFabLtAodyh8A9A This blog is about Thomas Vander Wal and the term Folksonomies. Which, I'll be honest, have never heard of until todays lecture. Foksonomy is the activity of sorting information into categories derived from the consensus of the information users. My question is...Is it useful? I think there are pros and cons, and the blog I posted earlier will help define these for you. For me it probably isn't as difficult as all this, I simply tag my friends in photos or comments and that's as far as I take it.
But a point was made during the lecture that made me think, with our ability to tag everything, have all these words lost their meaning on the internet? Have all of these words simply been categorised and that's it, it's certainly something to think about. Maybe we are taking Folksonomies too far, and categorising too much.
In terms of tagging and folksonomies, I would say they are more useful than not, and make our life on the internet far easier.