Interesting concern about new tools being created to obscure your search clickstream after the AOL’s search engine debacle. 

Right now - hardly anyone uses such tools - so there’s nothing much to worry about - but what if a lot of people started to use a new, and completely valid solution called TrackMeNot.

"It hides users’ actual search trails in a cloud of ‘ghost’ queries, significantly increasing the difficulty of aggregating such data into accurate or identifying user profiles."

That would put a monkey wrench into many of the keyword research tools .  I don’t think this will actually grow to become much of problem - you’d have to have several million people using TrackMeNot before results were affected.