Pete,

I would rethink this idea. I do several web pages (okay - hundreds), and
most of them I try to update as needed, many of them weekly. But think
about this - does a visitor really care when you site was updated, as
long as the information is up-to-date? What if you get busy and don't
have time (or the need) to update a page for three-six months. A
first-time visitor will see you haven't updated the page since October
3, 2007.

In reality, there is absolutely nothing to be gained but a whole lot to
be lost by using: Last updated on ....

Once again - don't add things to a web site to show off what you know.
Add things that will increase the knowledge of people who visit it.

Mike