Is Google a public utility? Do the words apply?
In Australia for many years the privately held power companies had an excellent time of it -- egregious anticompetitive behaviour including cross-state price fixing on a grand scale. Look up the name "NEMMCO" for a history. It's interesting, although not terribly pretty, and not a part of our history I'm proud of.
The result of all this unconstrained trading (Oooh... the power! The Power!) did not escape the notice of the people though and regulations were written. This is what turned a number of private companies into a public utility (oddly looked after by a private company, but hey, that's Australia!).
The point I'm turning here is that Google has a huge amount of influence, and a subtle but potentially catastrophic and unbalanced control over what is seen by a segment of the population that is nearly planetary in scope. If they don't adhere closely to their "Don't be evil!" motto then they will have regulations written to constrain them.
I'm utterly convinced that this would be a bad thing, too -- I believe that Google and other search engines are the equivalent of a free press and should forever remain apart from government control -- but not all control. The best newspapers were those that knew when to tell the government to go to hell, and would stand up for their principles and their customers and content providers.
Note that word -- it's a biggie. Principles. Google has at least one, and it's the main reason why I've chosen to use them in preference to others. If Yahoo or Alta Vista or others of that ilk copy it (is imitation always so bad?) then perhaps I'll be more eclectic in my choices. But a free press still matters to me, and a free Internet. And the Internet is one very, very big book to try to get through without an index.
"Don't be evil" is simple and unambiguious -- you might differ in what's evil and what isn't, but you'd always be able to go back to that simple statement and measure your behaviour against it.
In the long run, it just might be enough to keep Google a force for good, and out of the clutches of the regulators -- if they mean it, and if they keep their self-control.