I did as suggested and did a new install. I executed your command
sudo python -c "import urllib2; exec urllib2.urlopen('http://status.calibre-ebook.com/linux_installer').read(); main()"
The installation asked what directory calibre was in. I replied /usr/bin/calibre, as that is where the type command told me calibre was, and it said that was not a directory name. So I gave /usr/bin and now the %^&*( SOB has replaced by /usr/bin by a load of ^&*!
Is this "works as designs" or a great, bloody BUG?
I am not happy.