Gian-carlo or Giancarlo is the brother that died in the boating accident when Sofia was younger. I believe it was Tatum O'Neal's brother and Ryan O'Neal's son Griffin who caused it.
Apparently, those of you who have the issue of House & Garden with Sofia's apartment featured in it are lucky; I just visited the website for the magazine and it 'folded.'
In case anyone didn't know, Sofia helped to create 2 lip glosses for Three Custom Color: Doubles and SC 2004. They're under the 'Special Collections' part of the side menu.
And lastly, if you'd like to see Sofia's apartment 'on film' it was used in the movie "Broken English" by her friend Zoe Cassavetes as the character Audrey's apartment. The movie basically mirrors Sofia and Zoe's life; Audrey and her husband are pretty much based in many ways on Sofia and Spike Jonze.