What's scary is more people seem to be more concerned with the security of a convenience feature Google offered that is obviously OPT-IN than they are with the fact that their emails are sitting in plain text on servers all over the place open to any prying eyes that want to see them. Paranoia of large companies seems for supercede the stark realities of existing privacy holes so big you can drive a bus thru them.
This is real simple in that if you don't want to use the new feature on Google DON'T and if you're searching for articles on bomb construction or joining the Taliban you should probably stop that anyway as 'they' are watching you.
I'm suspecting this new feature will end up ultimately tied tighter to search engine technology that starts suggesting sites you're more likely to be interested in based on your site searching and selection habits similar to Amazon's product suggestion targetting.
If I'm right and this happens down the road it could be the end of SERPs as we know them.
For the record, I'm not signing up for "My Search History" any faster than I'm signing up for GMail. Don't need it, don't want it, don't really care about the related privacy issues either as I'm keeping my nose clean and wonder what makes everyone else so tense about this feature as they must be hiding something :)