I recently expressed some reservations about using surveys or questionnaires that were designed for a specific situation to try and gauge industry-wide conditions or to set a general baseline for standard practices. Jurgen Appelo has posted a survey that is designed to gauge the general state of agile/lean software development practice. I think it could be useful for that purpose, provided enough people answer it.
A very good point is that respondents can write additional comments. Most surveys provide radio buttons or check boxes only, and some of the items on the survey may be ambiguous, self-contradictory, or dependent on context. On Jurgen's survey, you can comment about that if you feel the items are unclear or subject to interpretation.