If it says ships in 4-6 weeks, then it means Amazon has non in stock within their warehouse. When you order it from Amazon, they have to send the order to LG, who then processes it, packages it, and then ships the unit to Amazon. When Amazon receives it, it is then sent to you.
I think I got lucky, because my invoice read "Ships in two weeks" when I placed my order, but then Amazon sent me an email saying they were delivering it a whole week early. They must have had someone cancel their order on the TV and it ended up in my hands.
My order said four to six weeks as well. I ordered it on June 15th, and they said they were out of stock, but they shipped it out very quickly once it became available and I had my tv in my room and installed by June 26th. So maybe you will get lucky as I did!