So which companies are at the forefront of spoken language systems research and marketing? Here is a list of companies involved in serious speech R&D:
MicroSoft: Speech Technology Research
http://research.microsoft.
com/research/srg/
SRI International: STAR lab and AI center
http://www.speech.sri.com/
http://www.ai.sri.com/natural-language/
Lucent Technologies: Multimedia Communications Research Lab
http://www.bell-labs.com/org/1133/Research/
Sun Microsystems: Speech Group
http://www.sun.com/research/
speech/
AT&T Labs Research: TTS Project and Natural Voices
http://www.research.att.com/
tts
http://www.naturalvoices.
att.com/
IBM: Human Language Technology and Voice Systems
http://www.research.ibm.com/
hlt/
http://www-4.ibm.com/software/speech/

And here are well-known companies with serious speech products:
Dragon Systems
http://www.dragonsys.com/
Nuance Communications
http://www.nuance.com/
Lernout & Hauspie
http://www.lhs.com/speechtech/

And we mustn't forget to mention these famous Australians!
Syrinx Speech Systems:
http://www.syrinx.com.au
Cochlear Ltd:
http://www.cochlear.com

For a list of these and all WWW resources on speech science and technology known to me please stop by my Spoken Language Systems page:
http://ciips.ee.uwa.edu.au/
~roberto/research/speech.php
or checkout the ASSTA WWW Links page:
http://www.assta.org/
assta_sites.php