Jennifer Mo is a character in the book All Tomorrow's Parties, by William Gibson. She is mentioned in passing throughout the book, although she died long before the events of the book take place, and is used mostly as a source of peripheral information. I would in fact not think the character of Jennifer Mo was noteworthy, except for the fact that while reading another work by Gibson, Virtual Light, I noticed that another periphereal character, J.D. Shapely, is used as a leitmotif, with his death and funeral described in the last chapter of the book.
Jennifer Mo is similarly mentioned and developed in the background, and a description of her is also used in one of the short concluding chapters of the book. She, along with one of the protagonists, was secretly used in a drug testing experiment while living in an orphanage. The drug involved, 5-SB, makes people aware of metanodal points, but also would cause psychotic obsessions with the drug users chosen metanodal point. This leads Jennifer Mo to commit suicide after kidnapping the focus of her obsession, an "astonishingly boring actor named Kevin Burke". The drug trial was secretly funded by Cody Harwood, a billionaire who uses the information from the trial to dose himself with the 5-SB, in an insane quest for power. Cody Harwood and Colin Laney, one of Jennifer's fellow orphans, then become enemies, which drives the plot of the book.
The book chronicles Laney's dying thoughts, which are of his first meeting with Jennifer at a federal orphanage. In his dying thoughts, he doesn't actually remember any conversation with her, and it is difficult to tell if Jennifer had any special place in Laney's affections. It instead just describes a single slice of memory, vivid and bright, without exterior meaning.
I think this dying scene is not accidental: "All Tomorrow's Parties" is a book about the development of the future into an Omega Point or singularity. Harwood and Laney are both being driven psychotic by their increasing perception of the universe as an all-encompassing web of relationships that can be manipulated, for better or for worse. But in Laney's dying moment, he is released from this, choosing to remember the simple moment of meeting another of his fellow orphans, and escaping from all the plots and schemes that will later cloud their lives. It is actually easy enough, I think, to form an omega point: slightly harder to observe and remember reality in all its simple glory.