According to Wired, this move comes from Republican legislators in the wake of a leak of a TSA operations manual.
In their letter to Homeland Security Secretary Janet Napolitano (.pdf) on Wednesday, Reps. Peter T. King (R – New York), Charles Dent (R – Pennsylvania) and Gus Bilirakis (R – Florida) asked, “How has the Department of Homeland Security and the Transportation Security Administration addressed the repeated reposting of this security manual to other websites, and what legal action, if any, can be taken to compel its removal?”
The TSA workers believed to have been involved in the leak were already put on leave. I suspect that internally, DHS and TSA are reviewing and tightening procedures. I think that is the scope of an appropriate response.
I am intensely wary of any sort of legislation like this as I strongly doubt that it would do anything to curtail the impact of such leaks and definitely would rob us of our critical 1st Amendment rights.