Yesterday in "Rhetoric, Intellectual Property, and the Internet," we examined Gorgias’ Encomium of Helen as an indicator of classical Greek attitudes toward authorship. One might argue that the final paragraph is particularly indicative of Gorgias’ view of himself as an author by Woodmansee’s defintion (solitary, originary, proprietary):

I have by means of speech removed disgrace from a woman; I have observed the procedure which I set up at the beginning of the speech; I have tried to end the injustice of blame and the ignorance of opinion; I wished to write a speech which would be a praise of Helen and a diversion to myself.

One might also argue that the text reads as the product of workshopping or a drunken multi-rhetor argument, as indicated by the multiple viewpoints addressed throughout the speech. (What if she was persuaded by words or speech? By appearances? By violence or unjust insult?)
I agree that Gorgias most likely did see himself as a solitary author of this text, and quite possibly as an originary author. I’m not so sure that he might have felt entirely proprietary about it. Undeniably, he views this as not just any encomium, but as a Gorgias encomium. However, it seems to me that pragmatic aspects of text distribution in oral-aural cultures also come into play here. The Greek alphabet was still under development during the late Greek Dark Ages (c. 700 BC) and early Attic period (600 - 400 BC), and was accessible to only a few privileged scholars. Homer’s works (and others of the period) were written for oral recitation; indeed, oral recitation was the storyteller’s only hope for immortality. Professional castes responded to this need: Greek mnemones (memorizers) existed as late as the fifth century B.C., and the rhapsodes (rhapsodists, or professional recitors) are thought to have continued longer than that. Ong devotes special consideration in Orality and Literacy to the persistent Homeric oral tradition, noting that "the narrator of the Iliad and the Odyssey is lost in the oral communalities: he never appears as 'I'" (159). The proprietary author would have been a nearly impossible construct, since the literature of the period was dependent on oral distribution for preservation.
Havelock examines the developing written preservation of these works, noting the existence of a few copies of the Homeric texts "for school use" ("Preface to Plato," 47). These 'authorized versions' remained rare, as teachers and rhapsodists used the texts "as a reference to correct [their] memory, but taught it orally to the population at large who memorized but never read it" (48). The students, in turn, perpetuated the oral recitation of the works. Like anything repeated endlessly, the epics and poetics were adapted slightly with each retelling, thus muddying the concept of a single author.
I’m certainly not a scholar of antiquities, classics, or Attic literacies, and most of what I know on the subject comes from Havelock and Ong. I’m merely a rhetorician interested in the conceptualization of intellectual property in oral-aural and newly literate cultures. Comments and corrections are welcome.