A Google design tweak being tested would see the bar at the top of Google.com, as well as the left panel with the search options remain in place as the user scrolls through search results.
Alex Chitu at the Google Operating System blog has shared a video from Alon Laudon of what it looks like:
It's a subtle, but helpful change in my opinion, and I would not be surprised to see this one become an actual feature. It would also help keep Google+ on the screen at all times (the notifications and share box). This would make it easy to share content at any time while on Google.
This kind of interface already exists on Google Image Search, as Chitu points out, and that comes with infinite scrolling. One has to wonder if this would open the door to infinite scrolling on regular search results as well. If so, that ought to be good for boosting those first page rankings. In all honesty, I can actually see this benefiting pages that would rank on the second or third page of results, because users wouldn't be required to click through to another page to see them. It's much easier to keep scrolling down.
I really can't see much negative about the fixed navigation or the possibility of infinite scrolling in search results. How about you?