In terms of user experience, i think that Google is doing a lot of good, with some truly innovative user interfaces. It is good that this Internet giant uses some of its resources to explore new functionality.

Our huge benefit is that even if some of the ideas are not so good, we all learn from these experiments and we sometimes even get enlightened by them.

I don't know how long the "Keyboard shortcuts" experiments is running or how many people are exposed to it, but it certainly an interesting one.

In the basis of this experiment there a few keyboard shortcuts that allow you to navigate between the results and the search box in a different way.

On the snapshot to the right (marked by the red arrow and   circle) you can see the user marker.

By using the keys "J" & "K" the user can move between   results, and even jump to the next results page (or the   previous).

When you reach a result that you want to click on it, simply press the key "O" or "Enter" and you will be sent to that      page.

Easy and somewhat intuitive.

In addition to these keys, there are 2 more important key to make the experience full: "/" - put the cursor in the search box, and "Esc" remove the cursor from the search box and sends you back to the results themselves. with these additional 2 keys, the experiment almost eliminate the need for the mouse cursor during a search.

Pros -

• Important tool for handicap people, who can not use the mouse.
• very intuitive, easy to learn, and easy to use.
• Improves the experience of Laptop users, in terms of reducing the need for the mouse (as some of us hate the built in laptop touch pad).
• Makes it easier to focus on a results and navigate between them, as the sensitivity of the mouse wheel is sometimes not easy to control and you scroll too fast or too slow between results. here you control the navigation between results, and cognitively i assume its easier and more efficient.

Cons -

• It is hard to see it catching up, when we are so used to the mouse and the scroll wheel.
• The specific key choices are rather weird - "J" goes downs and "K" goes up!   shouldn't it be the other way around?
• Why these keys anyway, these keys are not easy to locate as there is no anchor  next to them (for example its not near the "Enter" key, or on a corner of the keyboard), and this makes you need to look for the key whenever you want to use them.
• The sponsored links (as you can see on the right) are still positioned on the right    top corner of the screen now, but now positioned under the keyboard shortcuts legend. this can reduce the advertisement effect. I guess that only for the  experiment, this location is suitable. probably a better solution will be evolved if this ever goes public.
• A result is only highlighted by the small marker, and sometimes it is not noticeable enough, i think an addition highlight will assist in navigation (for example highlight   the background of the results the marker is on at the moment)

In conclusion -

I like this experiment a lot. It is very intuitive and it opened my mind to the fact that sometimes I can live without the mouse wheel. I do not think it will be implemented by many, but having another solution except the "Tab" button to use the keyboard to navigate in a site, is a real pleasure as it bring to mind the option for sites to give the users a choice if to use the mouse or the keyboard.