FCP.co has an article on Matrox’s Thunderbolt solution, which is an adapter to work with any of their existing MXO products for $199 or $100 if you by an MXO as well.
Of course that means only one Thunderbolt port, so this has to go at the end of your chain, but still pretty cool to get your old product with Thunderbolt, now if only someone releases a PCI thunderbolt card!