Pgpool2 doesn't use the slave for load balancing
I found this page http://lists.pgfoundry.org/pipermail/pgpool-general/2010-May/002711.html

They say that I need to remove file pgpool_status. I did it and pgpool works now with two nodes! Seems the file was created when I had not the second node and after pgpool just trusted this file all time. So removing this file solved the problem.