We, on the eDist staff, have never seen, nor heard of Linux or Unix support for Dragon from Nuance.  Probably because most Linux distributions are open source and free.  There is probably very little money in this for Nuance. 

In doing a little digging I have found some information that might be of help to anyone interested in attempting to utilize Speech Recognition in a UNIX/Linux environment.

There are some open source apps that allow you to use windows apps with Linux such as Wine.

Wine is a free and open source software application that aims to allow computer programs written for Microsoft Windows to run on Unix-like operating systems.

http://www.winehq.org/ 

In addition, the Linux community is very cool and giving and there are some voice recognition solutions out there not related to Nuance.  Here are a few of them.

http://cmusphinx.sourceforge.net/wiki/communicate/

http://julius.sourceforge.jp/en_index.php?q=index-en.html#feature

Additional information can be found at the following link:

http://en.wikipedia.org/wiki/Speech_recognition_in_Linux