I went in to CompUSA this afternoon to talk to one of the salesmen there that seems to have some sense, to ask him what his take on the delays was. I don't expect a store-level (let alone sales-floor level) employee to know anything definitive, but he reads as many rumor and news sites as I do, and he seems to have a decently analytical bent, so I find him a more-than-pleasant-enough sort to talk to about things Mac-ish.
He thinks that it was probably a production issue, which could have also been a quality-control issue, but noted that the 30 or so they had gotten in and sold (pre-ordered units) had all been apparently ok, with no issues reported yet. I asked him when he expected to see real units on the floor for people to just walk in and buy, of any variety, be they high, mid, or low end, and he mentioned that they were getting in them in weekly now, so I consider that a good sign. They even had 6 of them above and beyond the tail end of their pre-ordered units that they were getting set to put on the floor.
Generally, I trust people.. but a week ago, I was told by another employee at that same location that they had pre-orders deep enough to take another 6 weeks to fill.. so I asked him if he had one I could carry out the door right now.. I thought I was safe... nope... they had 6, just like he said.. so here I am with a new iMac. It's gonna look kinda silly sitting on the desk next to the dual 800 I bought 2 weeks ago.. but I'm sure I will find a use for it.
The point I was trying to get around to (yeah, I really did have one) was that whatever was holding them back, they seem to be coming in numbers, at long last. This is a Good Thing.