IBM has announced that they are releasing 500 of their patents to the open development community.  Speech related ones are below:

• US6199043 Conversation management in speech recognition interfaces
• US5649060 Automatic indexing and aligning of audio and text using speech recognition
• US5636325 Speech synthesis and analysis of dialects
• US6185529 Speech recognition aided by lateral profile image
• US5615299 Speech recognition using dynamic features
• US5615296 Continuous speech recognition and voice response system and method to enable conversational dialogues with microprocessors
• US5263117 Method and apparatus for finding the best splits in a decision tree for a language model for a speech recognizer
• US5222146 Speech recognition apparatus having a speech coder outputting acoustic prototype ranks

See: http://news.bbc.co.uk/2/hi/technology/4163975.stm and http://www.ibm.com/news/us/en/2005/01/patents.html for a list of patents.