With WordPress 2.3.1 we have the native tags support. I'm not a fan of tags. Even if it's a way to freely classify your articles, are your sure this classification is correct as having a simple set of categories?
There is any advantage for the readers? And as a SEO point of view? I don't know, really. I'm too lazy to remember the tag I used to avoid a tag "explosion" in my blog. Singular, plural, synonims are all different words (specially in non english languages) so the risk to split the articles between the tags "post" and "posts" or "woman" and "women".
What is your choice?
Other articles: Tags or categories? Lorelle explains, Post Layout, 5 Desiderata for WordPress, This blog now on WordPress 2.7
