(By the way, linking to Dropbox directly isn't strictly necessary. You can also go "the other way", choose your book in the Dropbox app, then tap the "Open in..." button in Dropbox, and select Marvin from the list. I've been using SugarSync with Marvin in this way, because all my Calibre folders are stored in SugarSync rather than Dropbox. Maybe one day Marvin will also link to SugarSync and Box.net directly.)
