Indeed. The more data points, the better. At least for speech recognition personalization for Google Voice Search, it is opt-in: http://support.google.com/android/bin/answer.py?hl=en&an...
Not so long ago, the primary goal of the 1-800-GOOG-411 service was to record people's voice queries for the purpose of bettering their voice recognition technology. After they got sufficient data samples, they discontinued the service.
http://www.infoworld.com/t/data-management/google-wants-your...
> "Google had stated that the company originally implemented GOOG-411 to build a large phoneme database from users' voice queries. This phoneme database, in turn, allowed Google engineers to refine and improve the speech recognition engine that Google uses to index audio content for searching."