If you are an AT&T customer looking forward to the release of a mysterious device called the Samsung Skyrocket HD, it's time to count your losses. The device, which was announced way back in January at AT&T's Developer Summit, has been canceled. AT&T has decided to forgo the device and focus on other products.
It's likely that the device wouldn't have been very unique in AT&T's lineup of phones, especially alongside the Galaxy S III. Resources will probably be diverted to the Galaxy S III, which still does not have a US release time frame aside from "summer." I imagine some prototype devices will end up on eBay in the wake of this.
Samsung hasn't said much about it, but here is the official statement as given to Engadget: "AT&T and Samsung have agreed to cancel plans to offer the Galaxy S II Skyrocket HD. We are concentrating resources on other products to bring exciting experiences to consumers." These exciting experiences are likely the Galaxy S III.