Xvoice is a project using the old software and codings of IBM’s ViaVoice. I was part of this mailing list for quite a few years but the project is essentially dead as they cannot find a current voice engine to power their software. The last update to their software was in 2007.
Linux users have another means of running speech recognition and that is to run Wine which emulates Windows then they can install a version of Dragon NaturallySpeaking. Not really effective but it is a possible alternative.
There are other OpenSource speech recognition projects out there such as the Julias system which works in Japanese. There are other speech models for Julias including English but basically you need to build your own model which reduces the usability of this system to developers and very experienced coders. Julias is the most up to date of the Open Source systems having the latest software released on August 1, 2012.