After months of secret restrictions, and promises that it would be allowed, 3G VoIP is officially back on the books with the new iPhone/iPad SDK. The app iCall (free, iTunes link) has these functions available immediately. You can bet that Skype, Vonage and other VoIP providers will follow suit soon. Given that the iPad has a microphone, this means you’ll be able to make at least some sort of calls from them.
The new SDK released yesterday has also revealed some other interesting tidbits. The iPad will be able to hook up to external monitors; there’s a file-sharing directory for both PC and Mac; iPhone OS 3.2 only runs on the iPad right now, but will probably come to the iPhone soon. Finally, and most intriguingly, it appears that the iPad has support for a camera. In the Contacts app, it still gives you the chance to take a photo for a contact.