We're not going to engage in too much wild speculation on this piece of information, but there are certainly a few raised eyebrows in Engadget-land right now. Apparently Plastic Logic is no longer offering pre-orders of its QUE proReader, as a tipster of ours discovered while trying to push through his order of the $799.99, 8GB / 3G version of the large-screen device. According to the order page "Pre-orders are sold out. QUE w