Well, I have firsthand recent knowledge, and the good news is, at least at LAX and PDX on UAL, you can travel pretty easily w/o an id. I forgot my purse over MLK weekend for my weekend trip to PDX (darn those early morning flights...I have such a hard time getting myself together). This meant no wallet, no form of ID whatsoever.

I had checked in online, and had my BP. Security at LAX told me to go to the "oversized baggage" line and have them reprint me a boarding pass with the SSSS on it. Did so, got a *very* light patdown and swabbing, and off I went. The whole process added about 3 minutes.

Coming back, I checked in at the kiosk, then went to the ticket desk and had them do the reprint with SSSS. Had a much more thorough pat down and full inspection of bag, but no bag dump. PDX tends to be a full shoe carnival airport anyway, so the whole thing only added about 10 minutes.

All in all, it was much better than I had anticipated, and I was still able to enjoy the weekend.