Kindle Fire and Calibre
I got my Fire today, and of course the first thing I wanted to do was put some books from my Calibre Library on it.
I use Ubuntu 11.10, and Ubuntu recognized the device as an external disk just fine. This is the same behavior I saw with my Kindle II.
Calibre however doesn't recognize it currently.
The good news is that I was able to copy books using the copy mobi to disk option. I copied the book into the books folder.