I was chatting with someone from HP's sales department today... Here is the transcript. Take it with a grain of salt.
Tim: Welcome to HP Chat, please tell me the nature of your visit to chat today? (ie: technical support, pre- sales question, purchase, or quote)
Guest: Hey Tim
Tim: Hello there!
Guest: I'm looking to get 20 new smartphones for my employees
Guest: the pre3 looks amazing
Guest: but my business has a sweet deal on Sprint. Will the Pre 3 be launched on Sprint?
Tim: I'm checking on that for you.
Tim: Thanks for waiting online and your patience.
Tim: Yes, pre3 will be available on sprint.
Guest: When will it be availble?
Tim: The "HP pre3 ." is the most awaiting model. But, unfortunately, we do not have any official information on the releasing / orderable date. However, it is been expected to be available at the end of May.
Guest: Thanks Tim
Guest: have a great day