Another tool worth mentioning is
http://www.knime.org/Its pros are a very mild learning curve, support for many libraries and tools (R, weka...) and nice GUI. It is open source and cross platform (based on Eclipse) and can connect to a variety of data sources including postgres.
I have used it for some projects with good satisfaction. This said, Talend or other tools capable of compiling their workflow are probably better performance wise.
