The iSlate or the Apple Tablet is going to have the iPhone OS and not the MacOS which is very dissapointing for most of the users. On Apple’s part, this is justified as the Mac OS does not have support for touch whereas the iPhone OS is completely designed for touch. The Apple tablet being completely touch enabled along with hand gestures is going to have the iPhoneOS. For many users this wouldn’t be a thing to cheer for as many people already own the iPod touch or the iPhone, why would they go for a device which is exactly like the iPhone but only has a larger screen and supports gestures? They would be able to run all the apps on their iPhone, then why should they purchase the tablet?
Apple told it’s developers to develop their apps now for a larger screen (mentioned in the below article). This is a hint that the iTablet is going to have the iPhoneOS.