I know that, what I meant was that there is information stored about the past, that a malicious application could not get otherwise (i.e. it can record stuff only from the moment it is installed).

On similar note, I rememember someone arguing that the baloo/nepomuk db was a security threat, I guess since it makes slightly easier to search among the files on the system for a string like "password".

Both claims are technically true, and in neither case I believe they are practically relevant, neither for security nor for privacy. I was nitpicking, I guess.