Here is a quick list of some of the best Thunderbolt Audio Interfaces available.
Universal Audio Apollo Thunderbolt I/O Card for Apollo duo and quad. Should be released late summer 2012, according to their customer service . Thanks for mentioning this, Tousana.
Apogee Symphony 64|Thunderbridge connects to Symphony I/O, and X-Symphony equipped AD-16X, DA-16X, Rosetta 800 & Rosetta 200 converters. Should arrive summer 2012, according to their site. Thanks for mentioning this, Avening.
Prismsound Orpheus connects with Sonnet Thunderbolt to Express card & Express card to firewire800 adaptor combination.. However, it doesn’t work on Thunderbolts peeds. Thanks for mentioning this, Avening.
Black Lion Audio Audio interface will feature some sort of thunderbolt connectivity, by word of mr. BLA himself.