Here's how I see it...

TSA itself is not unconstitutional. Searches at the airport are upheld and has been going on since the 70's. When you buy a plane ticket, you're consenting to a search at the checkpoint. This has been in effect since the 70's, and the only big difference nowadays is that a federal agency, as opposed to private security firms, are taking over the searches.

That said, some actions and policies of TSA can be considered unconstitutional, such as the no-ID policy. The liquid policy, while silly, isn't actually unconstitutional because it falls under the color of law. On the other hand, not having an ID and being subject to verification, especially for domestic flights, can be considered to be voiding current Terry-stop laws, when you do not have to present ID when asked. Federal law, however, is a complicated beast, especially with administrative policies. I still think the no-ID rule is silly and should either go away (no ID checks), or being given a SSSS when not having ID (no verification - anonymous travel). If I had to settle for a compromise, I would go for the old policy (no ID, you get a SSSS only).

Just my two cents.