How can I watch Blu-ray discs?

Please see the following official documentation for Bluray disc playback on Ubuntu:

It is actually possible if you use the media center application called xbmc which can be found here.

https://launchpad.net/~team-xbmc/+archive/ppa

After you have installed the package their is a plugin for xbmc to read bluray disks. The instructions are here.

http://bloggingabout.com/bluray-playback-xbmc-plugin.html

OMGUBUNTU.CO.UK also has a very simple script to get it setup with VLC also which is at the below link.

http://www.omgubuntu.co.uk/2010/10/easy-blu-ray-movie-playback-in-linux/

makemkv is what i use on linux to rip and then play blu-ray discs. It works very well, and it's free at the moment. Makemkv will convert any dvd or blu-ray disc to an mkv file. DVDs rip into files of around 5GB, while bluray disks will give you huge files of 30-40GB. From there, i use handbrake to compress the video (including several audio/subtitle tracks) for viewing on tv/ipad/laptop.

Installation instructions are here: http://www.makemkv.com/forum2/viewtopic.php?f=3&t=224