Over on Jogin (and elsewhere) there has been a lot of discussion of how to use headers.
My take is that headers are a structural element, and we define the structure before we apply the layout to it.
Thus, the H1 should always occur once on a page, and define the name/purpose of the page, without any particular relevance to the overal site (ie it can, if appropriate, be text relevant to the site, but thats meeting the specific needs of the page, its not relevant to the structure of the page).
This normally leads me to have html somewhat like this:
Home Page -
<h1 id=”pagetitle”>SITE TITLE</h1>
<div id=”subtitle”>a subtitle, if that is appropriate to this site</div>
… content …
and pages within the site like:
<div id=”pagetitle”>SITE TITLE</div>
<div id=”subtitle”>a subtitle, if that is appropriate to this site</div>
<h1>Page Title</h1>
… content …

I also tend to put headings, generally a h2, on my nav blocks, generally something exciting like ‘Navigation’ and then apply a style rule of display; none to it.

Sidenote: I’m wondering how much of this debate is being driven by the layout of blogs, when I see discussion of how to head ‘multiple entries’.
On a blog, if there are multiple entries, I would suggest that each of the entries is probably a h2 and there is probably an implied h1 of something like ‘my blog entries’. personally, II’d be applying display: none to that baby :)
Thanks to Mary-Helen for inspiring me to actually post :) Its been a while.