Planet 3.0 is attempt to do something genuinely useful and different in facilitating discussions about sustainability, and I am greatly encouraged to see it launched.
Me too! Eager to learn more about this fledgling endeavor, I clicked on the "About" category at the site. It reads (my emphasis):
Welcome to the Alpha release of Planet 3.0 a new effort in sustainability journalism. We are currently an invite only site, and are only sending invites to a select group of scientists and communicators. If you don't have an invite, check back later.
So an online site that presumably wants to get more people to think about and embrace sustainability concerns is an exclusive club. And some wonder why climate change remains a niche issue. [UPDATE: Michael Tobis explains in the comments that the About page was "stale" and he has since removed its original content. He also expands on his explanation here for the selectivity of the site's hoped-for community.]