As of just a while ago, Amazon US is announcing it's out of the Beatles in Stereo remaster box sets until after the 9/9/09 release date. You can visit the listing here to sign up for e-mail notification when the set is available again.
You can also sign up to be notified if Amazon gets more copies of the limited edition Beatles in Mono box. It's unknown if they will or not. However, I wouldn't be surprised if Amazon starts listing the mono set as available "new or used" from other sellers after the release date. It'll be interesting to see how much these go for. If the box is truly in short supply, prices could be very high.
So far, it looks as if the individual remastered albums are still available for pre-order at Amazon. Abbey Road is the top-selling entry, followed by "The White Album," and Sgt. Pepper.