IMO, I think Jill Whalen has hit it right on the bulls-eye with her topic “The Art of SEO (http://www.highrankings.com/issue105.htm#seo)” in her last newsletter. Bravisimo Jill! I think you are so right with your statement,
“SEO is much more of an art than a science. The science is only a small portion of it.”
where SEO is a lot more than the 12 or so typical on-page factors (out of the 100 or so). There are just so many things that play an important role that a single page with the a few nailed on-page factors will never be enough.

That is exactly why formulas won't work. People want formulas so they an just automate something as opposed to actually putting some real thought into it. In reality each web site is different. Pages are different. Competition is different. Goals are different. This requires one to ‘paint outside the lines’ and develop a strategy that is unique to the site, its goals and the obstacles that stand in the way of those goals.

SEO is an art at the moment. But it shouldn't be an art and it won't be an art. It will be very scientific and be a science, and will be teaching at elite universities. It has a long way to go to get there as VP of Google's technolgy said 95% of search engine technology has yet to be developed.

The academic fields that will contribute to search engine field I can think of would be:

marketing, information retrieval, MIS and etc.

The reason is the fundamental differences between other marketing fileds and search engine marketing. For SEO, we are against a few giant and sophisticated machines. If you know search engines' ranking algorithms (withour breaking into googleplex), you can rank higher withour any sort of experience or art. I'm aware of that high ranking is only part of search engine marketing.

By the time search engine marketing matures, it may not be called SEO at all. In a broad sense, search engine marketing is really about communications in a digital, interactive and hypermedium environment.