A similar trick that's nice is piping tar through ssh. Handy if you don't have rsync or something better around. Even handy for one file, since it preserves permissions, etc.
tar -cf - some/dir | ssh remote 'cd /place/to/go && tar -xvf -'
I love this trick. I was dealing with some old solaris boxes something like 15 years ago when I learned you could do this. I couldn't rsync, and had started off SCP'ing hundreds of thousands of files across but it was going to take an insane length of time. Asked one of the other sysadmins if they knew a better way and they pointed out you can pipe stuff in to ssh for the other side too. Every now and then this technique proves useful in unexpected ways :)
tar -cf - some/dir | ssh remote 'cd /place/to/go && tar -xvf -'