freejung - 10:49 pm on Jul 15, 2010 (gmt 0)

I've also noticed a lack of movement lately for on-page tweaks that I would have expected to make a difference, say 5 years ago.

I think that once you establish a certain baseline level of relevance (that is, once Google understands clearly that your page is indeed selling Pink Widgets, which I'm sure is clear from your title and other obvious factors like body text), after that it's pretty much down to off-page factors. Do your on-page tweaks really make the page more obviously about selling pink widgets than it already is? Seems unlikely. The on-site stuff like information architecture matters, but I think especially for competitive terms where all of the top sites have at least simi-decent SEO, your ranking is going to be primarily determined by off-site factors.