A company I do work for has hours upon hours of Camtasia screen recordings with instructors' voices. However, one of their clients is deaf. Manually adding captions to so much material would be horrendous.

Are there software solutions for this? Voice recognition / subtitling software?

If not, is there any workflow you might suggest to add captions?

UPDATE: Oooh, I just remembered I got CS5 Production Premium and they said some stuff about speech recognition being part of it. Do you think that might have an option for subtitles?

I'm not familiar with CS5 methods, but give it a try. Either way, voice recognition methods are not tried and true and you are going to have hours of corrections to take care of and lining up subtitles, etc. Be prepared for a torturous event. But, if CS5 can save you SOME time, it would be worth it.