I had a hard time finding good articles about how to install icinga with the new web based PHP interface on Ubuntu 12.04.
I didn't want to grab the sources and compile it. Not that I am not able to do that, but in my opinion it should be an easier way to install it. We are living in 2013 and not in the last century ...
Anyway, to make a long story short I found a very good step by step guide on askubuntu which worked for me exactly the way it was described.