Blockchain just started using btc-e pricing or bitstamp or a combination. I dont know but bitcoin holders on mt gox are about to take a hair cut.
I've been seeking an answer for the past two days:
https://bitcointalk.org/index.php?topic=274142.0Will there now be a mass exodus from Mt Gox due to this revelation? We can assume they're liquid, but if not they'll have the option of tapping Bitcoinica's funds.