Hi, Mr. albatross
Thank you for your mail.
I tried to reply to your question but the mail returned. So I put my answer on this BBS. I wish you get it.
Your question is about the word "blue pill" in the first scene of Revolutions. Right?
At the moment the crew is searching Niobe or Ghost inside Matrix from main deck on the Hammer - from real world. That means that they are watching monitors which display the information about the situation of Matrix. I think it is a kind of map which show location of a target in Matrix as a symbol like a dot.
First I thought that the crew call the symbol "pill" as a slang and the color shows the status of the target (blue is inactive or latest point they know... something like that).
However, as you pointed out, when I consider the word "pill" in context of the "red pill and blue pill" on the first Matrix, I get another interpretation.
Who take blue pill? Someone who (choose to) live within Matrix only. So the whole sentence would be this: "Nothin' but (the signs of people who took) blue pills." Yes, - "Blue pill" can be a slang that mean people living in Matrix only.
I think that the monitors in front of the operator should display information about people in Matrix - both Jack-ins (may be as a red dot) and "Blue pill"s (as blue dot :-)
This is Morpheus's explanation about red pill that Neo took in the first Matrix.
"The (RED) pill you took is part of a trace program. It's designed to disrupt your input/output carrier signals so we can pinpoint your location."
Why it is important to PINPOINT the location of the target? Of course, in order to jack out Matrix.
In other word, "Red pill" status shows availability of jack out. Who can jack out? Someone who jack IN. Then what about Blue pill? Remember that Morpheus knew where Neo was BEFORE taking the red pill. Some kind of information about people in Matrix must be available in a monitor in the Real World.