This is apparently due to reports of it bricking some phones. The update is able to be applied twice to the phone, which then crashes the entire OS. HTC and Sprint have pulled the update and promise to have it back when they iron out the bugs.
While the vast majority of consumers successfully downloaded and installed the most recent HTC EVO 4G software update, we have received a handful of reports from customers having some issues with the update. In light of this, HTC and Sprint have decided to temporarily halt distribution of this software release until we can investigate further. We expect to be able to resume software updates shortly.
