T-Mobile delays HTC 8X Windows Phone update

I know you were eagerly anticipating a new software update today and I wanted to give you a status update. In order to ensure the best possible experience with your device, we have temporarily delayed the release of the update to perform a few tweaks. We’re working hard to ensure that we get the update to you as quickly as possible.
So, no word on what happened or when the update will come, but we'll keep an eye out.
source: T-Mobile Support via WPCentral