Palm will unveil its long-awaited Pre smartphone June 6, and Apple’s next-generation iPhone is expected to hit the market shortly thereafter. So where are the smartphones based on Google’s Android platform, which is considered a potentially serious threat to the iPhone? Rumors have it that AT&T will unveil an Android smartphone from HTC in August; meanwhile, several vendors have announced that they’ll be making smartphones based on the open mobile operating system. There are also reports that Taiwanese smartphone powerhouse HTC will soon have an Android phone in China.