While the TSA deserves much of the criticism directed at it, it shouldn't be faulted for flagging one-way travelers for extra security screening. Think about it: if you're planning a suicide mission 9/11-style, then you don't need a return ticket. Sure, 99.99+% of one-way travelers are benign, but I see a justification for the TSA's concern.
As an aside, I myself got the one-way "SSSS" extra security stamp on my boarding pass when I was bumped by CO to WN on the return leg of a SAT-DAL trip. When CO purchased a return ticket for me on WN, the system treated my itinerary as a one-way because I was returning to my point of origin on a totally different carrier. Yeah, it was an inconvenience, but c'est la vie.
[This message has been edited by cAAl (edited 04-28-2003).]