Lightroom 4.3 RC still does not upload new files from Nikon D800 or D700. Images uploaded into LR3 are still in the Library but new photos are not readable. New images are not corrupted because they are viewable and download in Nikon View NX2 and Apple iPhoto.
Several versions of LR4 have been able to read the D700 and D800 raw files.
Using Nikon Transfer 1 on new camera NEFs is one way to corrupt them in ways that makes them unrecognizable to Adobe products.
Please upload one of these unrecognized files so others can take a look. If you don't have your own large-file storage, then sign up with http://www.dropbox.com or similar and upload one, there, then reply with the public download link, here.