Hmm...now that I've reread OotP, I realize that Luna never really did say she saw her mother die...Harry merely asked, "Who did you know that died?" and that's quite different, isn't it? Hmmm....in any case, I still feel that Harry should've been able to see them at the end of GoF, even if Cedric's death hadn't processed yet. That's not one of the conditions, is it? You've got to have seen death to see thestrals, not have seen it and come to grips with it as well. That was definitely a shoddy job of smoothing over, but she's done too much genius writing for me to really hold that one against her.
Alright, I'm peacing y'all out! I'm boycotting the net until Harry Potter and the Deathly Hallows is properly read!