I got this directly from the mbp reader homepage - seems it does not work anymore:
last Kindles (probably anyone updated, but confirmed with "Kindle DX") seem to store notes in a way that mbp_reader cannot deal with. I'm working in this issue, but it's a hard one, so I can't promise a solution.
Symptoms of this issue: when you run the program, the text file reports the number of notes, but nothing more, except the text you've written, if any. But no trace of ebook highlighted text.
Well, technically, it seems that new Kindle only stores a "pointer" to the text on the original book, instead of the highlighted text itself, as previous versions did. If you can help providing a way to access by position, the text of some ebooks kindle can read (.mobi, .prc ...), that would Greatly help!