A recent issue of Science contains a short piece on GPSO. If you're registered there, you'll find it here. It's in the "Random Samples" section of the October 31 issue, Volume 322, Issue 5902. From the piece:
At a time when some developed nations are paying citizens to bolster flagging birth-rates (Science, 30 June 2006, p. 1894), a grass-roots group of scientists and environmentalists is calling for a new push to limit human numbers.
Overpopulation is threatening life as we know it on the planet, say members of a movement called Global Population Speak Out (http://gpso.wordpress.com/), which aims to persuade at least 50 “respected voices” to “speak out in some way” about the problem for a month next year.
GPSO is bringing scientific voices worldwide to bear on the population issue. It's great to have the opportunity to alert a large portion of the scientific community to what we're doing.