While I have never formally worked as a technical writer, I am more than happy writing documentation either for other members of a development team or for users.
For the former case I have been one of the major contributors to my team’s wiki since we had one, and have also written Developer Guides and training presentations.
I can’t overstress my belief that [developers should write](link to blog about that — should be in my Pinboard), and that clear documentation implies a clear understanding.
As well as that, the developers I admire most in the public eye are those who write about the field. These are some of the people I would like to emulate, even if I haven’t always done so.