The estimated time clock on the Yosemite installer seems to have been coded by the Windows Vista team.
The installation got stuck at 3 minutes remaining for over 2 hours. Lost patience and rebooted the system, It started with 59 minutes remaining, and got stuck again at 3 minutes remaining for over 3 hours now.
The last log line in the Installer Log:
Container dmg is missing universal diagnostics. This install will continue attempting to preserve existing diagnostic software...
Help required.
2012 Macbook pro
Just hang in there. As ycrepeau pointed out, it seems to be related to an inefficient copying of files into /usr/local.
For reference, it took ~8 hours before mine finished (mid-2010 iMac), but I have 600k files in my /usr/local (combination of homebrew and texlive).
Checking the installation log, the installer started, 5 hours ago, to copy /usr/local sub directories one file at a time.
I have made an average of 10 files copied per second.
Since I have installed a lot of stuff in the /usr/local directory using Homebrew, added a lot of gems in my Ruby of Rails projects and use rvm to manage many versions of Ruby, I have a lot of these tiny files. Just with Latex or X-Windows packages and the dependency packages, there is more than 1.3 million files.
So, 40 hours to wait.
One issue (question) remains: what happened when the installer log shared buffer has reached its limit (128 x 1024 lines): did the installer continue to copy files or the logger creates an exception capable to stop the whole process?
This checker is not robust enough to cope with developer installs such as brew and/or latex and chokes leading to a long install time (or perhaps hanging completely)