Philip discuss this in some length in his post here.
The gist of it:
I'm starting a new company, and wanted to let you know. It's a big idea - something that actually depends on Second Life existing to get started...I have met Philip few times, and he is also the author of an intro to a forthcoming issue of the Journal of Virtual Worlds Research on Technology, Economy, and Standards. He is -- in my mind -- the father of modern 3d3d virtual worlds.
I will still be chairman, as I have been since leaving the job as CEO. The change is that I'm not going to be working full-time at Linden Lab anymore...
I must also admit that the CEO (mark) appearance with Phillip in most occasions was "interesting" at best. It seems that they are holding a different views on the roles of CEO and Chairperson.
The future of Second Life depends on the CEO and his team, and the board and their ability to direct the firm in the right direction. I'm hopeful.
Read more about it here