You wait ages for news on Torchwood and then you get to a point where it all seems to pile in at once. In recent weeks, we've learnt that Series 4 will be filmed in America, that there are new characters to look out, who the writers are (yay for Jane Espenson and John Fay) and now it seems that Series 4 has the title of The New World as well. Makes sense, given the international feel this new season will inevitably have.
In terms of the spoilers, it seems that Torchwood is a legend and Jack and Gwen get involved with Rex and Esther, after the latter pair are on the run for investigating some alien-related global issue. Russell T. Davies has also pointed out that the ten episodes will tell a self-contained story with Children Of Earth being used as a template. I hope it's not as grim as that 'template' to be honest.
Press Release: http://gallifreynewsbase.blogspot.com/2010/08/torchwood-new-world.html