Looks like I ruffled some feathers on kevin_standlee's pages with my interpretation of what the Hugo "Fan Writer" award should be. Many thanks to Kevin for succinct explanations of the award itself and how the nomination process works. I don't like to hog anyone else's LJ, so will move my part of that discussion here.
In a nutshell, there is a Hugo called Fan Writer, and the way it is worded in the group's constitution it seems clear to me that it was originally intended to be a way to recognize excellence in stories written by non-pro writer/fans in non-professional media (fanzines, semi-prozines, web journals, etc.) but it is also worded in such a way that anyone who publishes anything fannish in non-pro media is qualified for the award. As a result, it has been won very often by professional sci-fi writers whose work (both stories and fannish stuff - reviews, commentary, news, etc.) has appeared in non-pro media.
Something which reinforces the concept that pros are eligible for this award is there is a corresponding fan artist award, which explicitly states it cannot be won by a professional artist. There is no such statement in the Fan Writer description.
I'm not a member of the WSFS which runs the Hugo contest, so anything I say about the awards is purely my own humble opinion. I have great respect for these awards and the folks who are behind them, otherwise I wouldn't bother saying anything about them.
The WSFS constitution contains the Hugo rules, and those can be found at this link. See if you don't agree with me that, while it is not prohibited for professional writers to be eligible for this award, it would make sense to reserve this particular Hugo for amateur writers. Your comments are welcome.