Not just SEO. Adsense also pays a lot more attention to the title tag than anything else on the page (at least it did about a year ago, when I last experimented with it). If you want nice targeted ads, unfortunately stuffing keywords into your title is an effective way to get them.

> the fact remains that crudding up the title tag does actually provide tangible SEO benefits.

Source/study?

Sure. Here's a vacuum test study I performed on this very subject. Looks at the relative effects of words in URL, Title, Headings, and Body: http://www.mikeindustries.com/blog/archive/2006/01/the-round...

It's a little TLDR, but the point above is spelled out near the end in the final "conclusion". Cheers.

experience.