Planet13 - 2:49 am on Jan 20, 2012 (gmt 0)
But in all seriousness, is a "header" really that important?
While I agree that the header might not be the most significant part of a site, I think they might be quite helpful for branding.
Also, lots of ecommerce sites use the area for things like Security Badges, Toll Free numbers, etc. They may not be things that lead directly to sales, but they do help generate confidence in a site. they use that area for navigation as well as alerting customers to specials and sales.
If you go to the "big brand" sites, they make maximum use of the header area. On my screen (not huge, but not small) the header for those sites takes up about 1/3 of the screen real estate.
The thing that strikes me about this is that google seems to be taking a step backwards, toward onscreen factors, as opposed to social connectivity and user behavior. It sort of reminds me of back in the day when the ratio of content to html code in a document was a factor in ranking. It just seems like something that can be easily tweaked.