"2.x or higher"? Pffffft, it works fine on the eDGe. http://www.mediafire.com/?ij4qimmomid
Except the search utility for some reason (nothing happens when you hit go). But browse works and reading a book inside the App itself works basically just like the Kindle app: LCD only, flip pages by touching one side or the other. Except in my opinion it runs better than the kindle app; more smooth (go figure since it claims 2.x or higher).
EDIT: Downloading a book from inside the app appears to add some files to a folder called "BordersUS" and while there is a folder within called "epubs" the data for the book is not in epub format, but rather a series of html and xml files.
Now that said, if you just go to Borders.com
in the browser, you can download pdf or epub and they work fine too without the app, and they run on the eReader side. Though in some browsers, the download file may show as "index.php" but if you rename it to *.epub, it will open normally on the eInk side as its true epub self.