That is web 2.0, or the next generation of network.
Folksonomy, or tagging, could not deal with certain cases such that the sequence order of the words (tags) matters. [Example]
Further more, tagging could not understand. The system could find all pictures with triangle tags or circle tags, but it can't tell the difference between triangles and circles. The system could not learn to distinguish a triangle from circles by tags, even one hundred times.
Is tagging a solution? If we would like to find something by tags: First, we must speak the same languages (at least, could be translated). So a bird is not likely to find what it wants with human being's tags. Second, we have to specify enough tags. The word "mathematics" is not likely to help you find what you want. Although this might not be a problem. Third, precise tags. Certain groups of people would use different words to describe the same thing, or would they refer to different things with the same words. This could lead to some difficulties in finding information efficiently. Especially when certain group is very powerful, other smaller groups would submerge.