I'm definitely not a fan of every launch of Calibre showing me a prompt to update, but I'm also not sold on apps that upgrade without my express consent.
http://chocolatey.org/packages/calibre
I'm sure OS X has something similar, but I wouldn't know where to find it.
[0]: http://caskroom.io/ [1]: https://github.com/caskroom/homebrew-cask [2]: https://github.com/caskroom/homebrew-cask/blob/master/Casks/...
Currently I'm using an alias to clear the old binary and download the new one. [1]
[0] https://github.com/caskroom/homebrew-cask/issues/309
[1] https://blog.notmyhostna.me/make-calibre-updates-less-annoyi...
More recently my reading habits have changed and I much prefer to go directly for my books on my desktop. I've uninstalled calibre now. All I really need is a cli or a basic client (much like ncmpc for mpd) for my books. I'm looking for something along those lines, and am also planning to do a hobby project for that if the urge grows.
[0] On every Arch Linux update.