Google Tests an Interface Optimized for Infinite Scrolling
googlesystem.blogspot.com
googlesystem.blogspot.com
The nice thing about Google Images infinite scrolling is that they combine it with pagination.
The key phrase in the article is "setting the stage". Google hasn't switched to infinite scroll yet, but with a fixed header it seems most likely for them to do so soon.
My guess is that the pagination controls are there to accomodate people with JavaScript disabled.
I see this as "the revenge of designers" -- having anything permanently taking up the vertical space was pushed from "designers" for years and it always reduced usability for me. I'd prefer to see the results, not immense fixed space that doesn't contain anything. The picture is telling -- the permanent menu bar and the huge empty space around the search box and logo.
It would be interesting if spoofing your user-agent would get you the other half of the way.
If you're using TabMixPlus, there may be an add-on that gives you better performance.
Does it suck for those in the ever-decreasing minority? Yep. Is it worth it? Absolutely.
No, it's not. http://browsersize.googlelabs.com/
Strange that "position: fixed" hasn't found its way to popular websites before now. It's been supported by major browsers since the early zeroes (or late nineties?), the only exception being IE (for which you can easily make a fix).
Here's a page from ten years ago (!) describing "position: fixed": http://www.w3.org/Style/Examples/007/menus
The only fixed that I can handle is a fixed background if there is a large difference in contrast between the page background and main content background.
I hope this does not become a norm.