Why not post this in a new topic thread? I mean, what did you expect to find when you visited a thread entitled, "Space Needle"?
To answer your question, even if they were compatible, I'm sure there would be copyright issues with importing sc4 3d renderings into civ4. Otherwise I'm sure they'd be all for it. In fact, I'd love to see some sort of combination of the two games, and perhaps even throw the Sims into the mix while you're at it. Think about it: You can play a civilization, then zoom to a city to manage like in Sim City, then perhaps make a family and move it into that city somewhere. And the actions in the other two tiers would affect them; i.e. if taxes are raised, the family's income goes down slightly; and if the city is captured, well, maybe the male gets drafted into the occupying infantry or something.
It'll never happen, not in a million years. But it would be so cool! Almost as cool as Seattle....