I just read an interesting post on the The Sea Monster blog. The blog entry discussed whether junior scientists should be involved in advocacy.
Have a look at the post at: http://theseamonster.net/2012/04/weighing-advocacy-and-objectivity-as-a-junior-scientist/
Certainly some food for thought. I personally agree with the comments made by Matthew Ayres. I think this response does however split hairs with regards to definitions relating to certain language or terms. But my thoughts are if you informed (no matter whether a junior scientist or not) it is important to tell the masses, including policy makers, the information you hold.
I find many pure scientists are hesitant to provide information on their findings until the full process of their science has run its course. The world, however, does not wait for this process and policy makers tend to make public policy based on gut feelings, the loudest voices or quasi-science. It is therefore important for the scientists to be more actively involved in this process.
Many people in my field (policy-led environmental profession/quasi-science) now discuss the importance of making decisions now and apologise later. This seems to be how 'the world' and 'policy' seems to work these days.
As such, I think it is important for scientists to reveal information about their findings and research prior to the end of the pure science process and if something that has been conveyed to the public that isn't quite right at the end of the process, then inform the public of the complete picture at that point. People may have even forgotten the original information, given we all have two second attention spans these days.