You are right - an amazing Constitutional question. And if SCOTUS ever hears the case, I hope to be there, I live right outside DC (12/1/08 is just the deadline for Obama’s response to Berg’s suit).
If Obama was found ineligible, the next set of eligible electors is for McCain. Presumably, they would vote 538-0.
As for Biden, I think he could make the case for his electors being eligible - but SCOTUS would have to decide. If they were determined eligible, I would assume they would vote Biden VP at the current Electoral College count. The Electoral College votes for POTUS and VP separately (12th Amendment).
If Obama was ineligible and Biden was declared null and void (as a result of the FULL ticket being voided), then the next set of eligible electors is for McCain/Palin. They would be seated and presumably vote 538-0 for both McCain and Palin.
Wow, think of the TV audience this could generate — enough viewership to save the networks (and maybe a few newspapers)?
Now THAT is an interesting take on it. Republican President, Dem VP. Been awhile since that happened.