You're correct about Intrade's requirement to front the money to cover your position in all cases until the contract ends or your sell it.

However:

The current bids sum to quite a bit more than 100 so by selling contracts on every outcome you should receive more than 100 and you will never have to pay out more than 100 so you should have a guaranteed profit.

That doesn't follow. Even if the bids sum to more than a hundred, you have put up the other fraction of $10 for all of those n contracts. With a lot of the bids very low, then in order to cover all possibilities, you have to put up over $9 on many, and so it looks like you will have to front more than $10*(n-1), making it a loss from the beginning.

Yes, I ran the numbers in several cases like this in the '08 election.