The latest issue of the Notices of the AMS contains the first part of a long biographical article about Grothendieck written by Allyn Jackson. Evidently Winfried Scharlau is writing a biography of Grothendieck, and Jackson’s article is partially based on materials he has gathered. Much of this material is brought together at a website maintained by the “Grothendieck Circle”.
This issue of the Notices also contains a short expository piece on one of the most abstract ideas due to Grothendieck, that of a “topos”. Illusie was a student of Grothendieck’s, and Jackson’s article has some of his reminiscences about what that experience was like. Illusie’s piece is not very accessible; a better place to try and get some feeling for these ideas is Pierre Cartier’s Bulletin article.