Tagging

Tagging is familiar to me as it is used on Facebook, Flickr, and Library Thing. These are the sites I tag currently. Should it be used in the library? It seems too open to me for use in the library, but that is probably me being stuck in the dark ages of Dewey Decimal. Our ILS has recently partnered with Library Thing and so we may be exploring tags for our OPAC in the near future. I am on the fence really with the whole issue of tagging. At this point, I don't feel that it should be encouraged in a library setting.