It probably was not fair of me to start a discussion on authorial intention with a Barthes quote, my attempt at intertextual play perhaps was confusing, but for Barthes there is no more author, that is for sure. However, this does not mean what Sameer has to say is irrelevant, it just means I need more time to think it through, until then let me clarify Barthes position.
While it may have been Kristeva's gloss on Bakhtin which eventually led to the term intertextuality, it is Barthes who has played the term and developed it into a theory of posts-structuralism. For Barthes the key to intertextuality is to get away from a modernist view of the text. To this end he employs the term 'work' as a replacement of 'text':
A work is a finished object, something computable, which can occupy a physical space (take its place, for example, on the shelves of a library); the text is a methodological field. One cannot, therefore, count up texts, at least not in any regular way; all one can say is that in such and-such a work, there is, or there isn't, some text. 'The work is held in the hand, the text in language'.
The text is a process in signification rather than a medium within which meaning is secured and stabilized, writing for Barthes opens the sign up to a Derrida like explosion, infinite and yet always already deferred dimension of meaning. Barthes' theory of the text, therefore, involves a theory of intertextuality, in that the text not only sets in motion a plurality of meanings but is also woven out of numerous discourses and spun from already existent meaning. Barthes intertextual text is:
woven entirely with citations, references, echoes, cultural languages (what language is not?) antecedent or contemporary, which cut across it through and through in a vast stereophony. The intertextual in which every text is held, it itself being the text-between of another text, is not to be confused with some origin of the text: to try to find that 'sources', the 'influences' of a work, is to fall in with the myth of filiation; the citations which go to make up a text are anonymous, untraceable, and yet already read: they are quotations without inverted commas.Unlike Kristeva, for whom the reader is the absent mediator-translator, Barthes reader is the body of mediation or medium for the texts effects to come into play. The reader is not a passive vehicle, not an echo chamber, but rather the regent of the text. The author then is an arranger or compiler of the always already written likewise the text is, then, 'a tissue of quotations drawn from the innumerable centers of culture.'
It is important for Barthes that one recognize that textual meaning is not created from an author combining a signifier with the signified, the Barthesian concept of the intertextual, does not mean we can simply move to the intertextual level of the signifier and signified. To say that the text is constructed from a mosaic of quotations does not mean we can find a text's pretexts and then view them as the signified of the texts signifiers. The inter-texts, other works of literature, other kinds of texts, are themselves intertextual constructs, and are themselves able to offer us nothing more than signifiers.
For Barthes the pleasure of the text is to follow the 'derive,' the drift of a ship off coarse, to see where it might take you, or where you might take it. The reader then is to chase the pleasure principle through the most deviatory routes, and play with other texts in a counter-directional manner. Unlike Kristeva who ultimately sought from the dialogical nature of intertexts the ability for ideological critique, in Barthes one gets the sense that the only redeeming value of texts is how they play, or as Mary Orr has aptly put it, the brilliance in Barthes is '....the choreography of the intertext as ephemeral and sensate, the white heat of pyrotechnics.'
 Roland Barthes, "Theory of the Text," in Untying the Text: A Post-Structuralist Reader, ed. Robert Young (London: Routledge and Kegan Paul, 1981), 39.
 Allen, Intertextuality, 65.
 Barthes, Image - Music - Text, 160.
 Orr, Intertextuality, 34, 35.
 Roland Barthes, "The Death of the Author," in Image - Music - Text (Fontana, 1977), 146.
 Allen, Intertextuality, 73.
 Orr, Intertextuality, 37.
 Orr, Intertextuality, 40.