Dev Kits having been shipping since April, but they have ran into all sorts of issues. They do seem to be somewhat sorted for North American orders though. I have not tried mine yet as I ONLY just got it today, so waiting to go home to give it a thorough test run.
If you do a pre-order on the Oculus site, they say that the new orders are set for shipping in August, which they should be on time for so far, unless they run into another customs issue or something.