With the Solvay Centenary conference now finished for over a week, some information has been posted about it on the Solvay Institute web-site, where you can see a group picture of the attendees on the main page. Lisa Randall’s comment comparing the gender balance to that at the first conference is actually rather restrained, given that the fraction of women (2.9%, 2 out of 69, Randall and Silverstein) is smaller now than back in 1911 (4.1%, 1 out of 24, Skłodowska-Curie). Oddly, only women working in extra dimensions seem to have made the cut.
The schedule of talks is here. Perhaps someday we’ll see proceedings of the conference and learn what was in the talks and discussions. For now, this page has links to some outlines of the rapporteur talks. There were two separate sessions related to quantum computing (here and here), as well as sessions on condensed matter, particle physics, quantum gravity and string theory.
The string theory talks seem to have just been about possible applications to condensed matter and to quantum gravity, rather than about using string theory to get a unified theory. Witten attended, but appears not to have given a talk of any kind.