Thinking of last week's concert, and plenty of other concerts I've attended, I must rant about the silliness of encores. No one is fooled. It doesn't take a lot of awareness to notice the concert is over only when the house lights turn back on. An empty stage, with the concert hall or arena still dark, means the band will come back, no matter how little you cheer.
It's even worse when the band doesn't play their best-known song in the main set. You know they're not going to leave the stage without playing their biggest hit. (I remember a review of Joan Osborne, known for one song only, making just this point.) In my opinion, encores should be songs with special meaning, like an early hit, a cult classic first release, or the like. Of all the concerts I've seen, one of the few to actually play their popular songs first was Inspiral Carpets, opening with Generations and playing Two Worlds Collide early, both songs then active on MTV's 120 Minutes.
When I saw Freezepop perform in February, they mocked the concept of encores. I appreciated it greatly.