What makes the Baigent vs. Brown lawsuit interesting is not that it's basically over a pun and a historical coincidence. In French "san greal" means "holy grail" and "sang real" means "royal blood." At the same time, much of the Anglo Saxon rooted Arthurian Legends were preserved by the French speaking Norman rulers of England, the Norman's being descendants of the viking invaders of Ireland, Great Britain, and Gaul late in the first millenium. The historical coincidence, combined with the coincidental fact that there was a major Templar presence in medieval Normandy, has for hundreds of years been the basis numerous tall tales about Templar conspiracies encoded in Holy Grail myths.
Rather, what is interesting about the lawsuit is that there was a much better book than The Da Vinci Code written by Umberto Eco in the eighties that the Holy Blood, Holy Grail authors have never seemed the least concerned about. Maybe that's because Foucault's Pendulum covers much of the same ground as The Da Vinci Code in a satirical way—weaving together paranoia, insanity, and modern day power lust into a complex and fascinating narrative. Whereas Brown's novel treats the legendary Templar stories about the Holy Grail as a hidden truth awaiting discovery—which, were it true, would make it one of the worst kept secrets in history—Eco opts to explore the ways in which semiotics and deconstruction can go wrong and lead otherwise intelligent people into irrational paranoia and truly stupid behavior.