It looks like there will never be an Atmega649p. I'm probably the only one who wanted to use it, so that could explain why Atmel dropped it.
They used to have it listed on their site and I have the migration document, but no more. Digikey used to list it with a ship date estimate of 01/27/2007 and the note "Delivery Date Past Due". But it's no longer listed.
I think I will survive this disastrous turn of events though. So far all my code will fit into a mega329p and if it doesn't in the future there is always the mega649 (without the p).
It surprises me actually. I assumed all the non pico power chips would be superseded with the pico power ones. Apparently they made an exception for this chip, probably because Atmel doesn't like me. :)