http://www.realityloop.com/blog/2009/05/24/fixing-gd-image-rotation-drupal-6-ubuntu-server-810

Thanks a lot for this really good quick fix to gd library in ubuntu.

I modified the first two lines:
deb http://packages.dotdeb.org stable all deb-src deb http://packages.dotdeb.org stable all
I also noticed that the /etc/apt/sources.lst file in ubuntu is called sources.list