Maybe not the first person to point out the "cabinet-of-curiosities" analogy, as he himself admits, but surely one of the most fluent explanations, Julian Dibbell explains why weblogs are the modern equivalent of Renaissance cabinets of curiosities, or Wunderkammern:

"The genealogy of Web logs points not to the world of letters but to the early history of museums -- to the "cabinet of wonders," or Wunderkammer, that marked the scientific landscape of Renaissance modernity: a random collection of strange, compelling objects, typically compiled and owned by a learned, well-off gentleman. A set of ostrich feathers, a few rare shells, a South Pacific coral carving, a mummified mermaid -- the Wunderkammer mingled fact and legend promiscuously, reflecting European civilization’s dazed and wondering attempts to assimilate the glut of physical data that science and exploration were then unleashing. Just so, the Web log reflects our own attempts to assimilate the glut of immaterial data loosed upon us by the "discovery" of the networked world."