David Weinberger has done this blog the honor of calling it "fascinating." He makes this comment in the context of his report on a recent Harvard conference on the book. I wish I'd know about it, as I could have made a trip across the river and not only learned more about the history of the book, but also met David himself.
In any case, the blog entry also contains a picture of a cabinet for note-taking by Vincent Placcius with the comment: "The cabinet was designed by Vincentius Placcius. It had 3,000 hooks for topics, each with places where you could hang scraps of paper with notes pertaining to those topics." Well, actually this is not quite true. What is true is that Placcius published in 1689 a book called De arte excerpendi: Vom Gelahrten Buchhalten (Stockholm/Hamburg): "On the Art of Excerpting. Of [the Method] of Learned Bookkeeping."  In it, he described not just John Locke's method of making common-place books and other methods of keeping notes, but also included an anonymous treatise about an "arca studiorum" without (perhaps) all-too clearly identifying it as not being his own. The manuscript of the treatise is now to be found in the British Library.
Noel Malcolm, in his "Thomas Harrison and his `Ark of Studies': An Episode in the History of the Organization of Knowledge," The Seventeenth Century 19 (2004), pp. 196-232, does a good job tracing the manuscript to the circle around Hartli(e)b (ca. 1600 – 1662), a German, who lived in England, and who is known as a polymath close to Comenius.
Hartlib knew Joachim Jungius. Thus he wrote to Robert Boyle: "Dr. Jungius of Hamburgh, one of the best logicians in all Germany. For he conceives if that art were truly understood and applied, not only botanical, but all real studies whatsoever would flourish more than they have done since the fall of Adam." Boyle does not seem to have agreed, but this does not matter here. What matters is that it is likely that the manuscript about the "arca studiorum" came to Placcius by way of Hartlib, for Placcius was a student of Jungius and he was also acquainted with Johann Adolf Tassius, Jungius' closest friend, who also had close connections with Hartlib and Comenius.
Leibniz in turn was deeply influenced by Jungius and his circle, and not just in his method of note-taking. A government official in Hannover had an "Ark of Study" built for his own purposes, which Leibniz bought after the latter's death. This is where he kept his many notes, though probably not a million.
Too bad that these notes were dropped on the floor after Leibniz's death and now present just an unsorted jumble of "miscellaneous" notes :)
In any case, while Placcius also commented on the literary chest as described in the manuscript, suggested improvements, and also seems to have built one, he can hardly be said to have designed it. At most, he tweaked the design:
1. The book seems to have circulated in manuscript form long before it was published.
2. "Manuscriptum ipsum exhibitum anonymi ..." See also p. 121, where he says: "Scrinium hoc inventionis mea non est," i.e. "this chest has not been invented by me." On the next page he actually refers to Tassius as the person who communicated the manuscript to him. And on p. 123 he clearly states what he has added himself. See also p. 132.
3. Vielmehr schaffte er sich nachher einen besondern Schrank an, seine Excerpta aufzubewahren; womit es diese Bewandtniß hat. Vincentius Placcius gab de arte excerpendi, vom gelehrten Buchhalten, 1689 zu Hamburg ein Buch in 8. heraus, worin er allerhand Methoden des Excerpierens beybringet. Membr. III, p. 150 wird sein hierzu angegebener Schrank in Kupfer vorgestellt. Nach dieser Invention ließ sich der Hannöverische Secretair Clacius einen gleichförmigen Schrank verfertigen. Nach dessen Tode kaufte ihn Herr von Leibniz. Und dies ist der so genannte Leibnizische ,Exzerpir-Schrank, welcher nunmehr in der königl. Bibliothek aufbehalten wird.