You won’t be able to install the iPhone OS 4.0 on your iPad this summer. No, you’ll have to wait some more months, because Apple has announced it will be available this fall.
While I can understand that the iPad has just been released and they’re badly working on the iPhone version right now, before the keynote started I was hoping there would be a contemporary release for both the devices. Turns out we’ll have to wait instead, and keep our iPads without multitasking. (Well, until jailbreak will come).
All in all, like I said in the live chat today, I expect Apple to change the name of iPhone OS to, at least, iPad OS for the new device.