Thanks wicket!
actually when I clicked on your link, Konqueror told me its "<2>" (= second window on same URL). Alas hynix is not really easy to approach for what they offer, you seem to have to call them or mail them. The MCP NAND+RAM package quoted on your 2nd link is a 1GByte NAND plus 512MB RAM. We need 1GByte RAM and we don't care too much about NAND, though of course a 512+MB of NAND on same package would be more than welcome. Anyway we can do NAND on discrete chip, while RAM interface is only available on PoP balls of DM3730 in the CBP package we need to use. We are pondering to go for CUS package (no PoP at all) but that would cost us a UART and a McBSP :-/

PS: the micron 8Gbit density PoP RAM
datasheet
again only states 2Gbit density, that's maybe why I failed on micron's components when searching for a chip 8 weeks ago.

BTW there's a tiny detail that makes our life as hw-engineers a whole lot harder than sw-engineers usually understand it was: when we decide for a component, then we need to know ONEHUNDRED PERCENT that it will fit and match and work. Then we have to spend a lot of money and time to *get* the component and integrate it into the design. And if we fail and picked the wrong component, we easily can burn 100s of k$. IOW we must act impeccable. Any OOOPS is a killer. While software engineers just deploy a patch to fix their oopsies ;-)
/j