"So are tags and collaborative filtering a marriage made in heaven? It's
a promising approach, but there are challenges in making it work - some
challenges inherent to tagging, and other challenges inherent to
collaborative filtering. The question is - does the combination of
tagging and collaborative filtering solve those challenges, or only
make it worse? I don't have any magic bullets (if you were looking for
an easy answer, stop reading now.) Instead I have a bunch of
observations in no particular order."