Sprint has published a website with wireless partner Bluefish for people that wish to be notified when the HTC Diamond has is made available for purchase. According to the website, this waiting list isn't a guarantee hold for the device, it's just for notification purposes. But if you can't wait to get your hands on the Diamond, Sprints empowering you to be one of the first here.
https://bluefish.sprint.com/promo/wm_htc_touch_diamond_promo.cfm