I think this should be done for searching purposes. At least the Teacher or Wiki Initiator should be able to determine the Keywords for the initial Wiki and/or the Student. Again I am for the teacher being able to make this determination (Student or only Teacher input for Keywords). Keywords should be able to be adjusted later if necessary and reflected in the "Page Information" by whoever is given access to do this. The discussion on the Wiki page(s) can go in any intended and needed direction, but there should be someway to formally classify or describe them as well. Also, I am keeping in mind that Moodle is heading toward an XML road and metadata will probably play a role in a future comprehensive site search engine. At least that is my feeling about it.
Anybody else have thoughts on this matter??