Barnes & Noble released its quarterly and full fiscal year results this week, and it doesn’t really seem to have picked up that much business from the shutdown of Borders.  Core comparable bookstore sales, excluding Nook products, were up 6.9% for the quarter (ended April 28th) and .7% for the year.  B&N attributed the increases to the Borders closing, Hunger Games and Fifty Shades of Gray
B&N’s retail sales for the year were around $4.9 billion, so the .7% increase amounts to less than $35 million. Borders began closing over 600 stores in February of 2011 (see "Borders files Chapter 11"), and finished its liquidation last September.  B&N did eke out a 4% increase in book sales over the holiday quarter (see "B&N Grows over Holidays"), but the total dollars involved are a small fraction of the sales that used to be made by Borders.
Of course, the fact that Barnes & Noble has been unsuccessful at capturing the bulk of Borders’ sales means that there’s more opportunity for independent retailers such as comic stores (see "Manga after Borders"), but it seems that the loss of over 600 doors where books were sold is going to have a long-term negative impact on book sales of significant scale.