Google is not taking any chances and is censoring all profanity on their Nexus One speech-to-text engine. 

They have replaced the most common swear words with ‘####’.  Google wants to avoid any situation where the user pronounces a word and the speech-to-text engine misinterprets it and inadvertently tells your boss to go #### himself. 

It may also be a good idea when telling ‘mom’ about the new truck,  but not so good when telling off your ex.  A better  idea would have been an on/off option.  ‘Censor on please’ when calling mom;  ‘Censor off’ when calling the a######.