I'd be interested to see the responses from experts in the field. I guess a really important starting point when considering such questions is to acknowledge that sign languages (of which there are many) are complete and rich languages the same as any other. Just as interpreting or translating from one spoken language to another is a complex activity, so it is for interpreting from a spoken to a SL or vice versa. The World Deaf Federation has a good introduction to Sign Language (see link).
Just as we may find machine/software-based translation useful when wishing to understand text/speech from another (spoken) language, we also quickly recognise that such software generally does not allow a high level of accuracy, or transmit many of the nuances that may exist in the original. I'm guessing the same challenges would exist for machine/software-based techniques for a spoken language to a sign language.
Anyway, I'd be interested to learn more from others.