The wikileaks cables exist in grey zone; it's they were never released by the US Government, but they are public. Generally speaking if you are not and do not plan on being an employee with a mandated security clearance, you have nothing to worry about. If however, you do have or want to acquire clearance you should not look at Wikileaks since you will be violating the terms under which clearance is granted.

Also, elements of the intelligence community have made statements that suggest that applicants to some government positions could be refused if they tweet or say anything about Wikileaks. [1]

1. http://dailycaller.com/2010/12/09/schools-warn-students-not-...