That's what I've heard too, Although we keep hearing vague references of what is to come [ie: webisodes / movies] that it might be eas to get our wires crossed...
Looks like the first half of season 4 will get it's own dvd release too. I figured they'd wait til the end. looks like it'll be seasons 4.0 and 4.5. I'd always wondered why season 2 was called 2.0 but none of the rest were titled that way...