Who was Matilda?

[Poetaster]

At the end of Purgatorio, Dante meets Matilda in the earthly paradise. My question is simple: who is she? What was her significance? Has anyone any idea?

[Lykren]

"Here Dante meets Matilda, a woman whose literal and allegorical identity "is perhaps the most tantalizing problem in the Comedy."" - Wikipedia (the quote is by Dorothy Sayers).

Wikipedia notes further, "Critics up to the early twentieth century have connected her with the historical Matilda of Tuscany, but others suggested a connection with the dream of Leah in Canto XXVII." References include Lawrence Binyon and Mark Musa.