This (probably) won't discuss the technical problem, but http://www.bitcoinity.org/markets will let you track Bitcoin prices.
The answer to the question I was trying to ask is https://coinbase.com/network/blocks which enables me to check in on how far behind the future legitimate blockchain is (7 blocks at time of writing).
http://blockchain.info/ is updated live.
As you can see, the 0.7 chain has already overtaken the 0.8 chain, and clients are now resubmitting transactions into the 0.7 chain.