I just received information from a very reliable internal Sprint source that there is a delay occurring with the shipments of the EVO LTE pre-orders. According to the source, the delay is being caused by HTC and may impact shipments going out as late as May 25th. This may be the cause of the EVO LTE pre-order statuses being changed yesterday for many customers to "back-ordered."
What is not clear yet at this time, if this affects all the pre-orders, or some of the pre-orders. It may be related to the quantities that Sprint will receive from HTC and when. However, there is a reference to software issues being the cause. We will bring you more information as we learn it.
EDIT 11:40 AM MDT: The source believes this will delay the launch to be as late as May 25th. Therefore, it affects stores and third parties as well. Will update with more info as we learn it.