A simple `tar -xvf` can replace the separate `gunzip` and `tar` processes.
pushd /tmp && \
curl 'http://downloads.sourceforge.net/project/tmux/tmux/tmux-1.8/tmux-1.8.tar.gz?r=http%3A%2F%2Ftmux.sourceforge.net%2F&ts=1364579710&use_mirror=garr'| tar xvf && \
cd tmux-1.8 && \
./configure --prefix=~/installs/tmux-1.8 && \
mkdir ~/installs && \
make && \
make install && \
popd