Every day companies like Google and Yahoo do things which don't have a directly measurable benefit. Why does Yahoo put out YUI, Hadoop, YTS for free? Why does

Every day companies like Google and Yahoo do things which don't have a directly measurable benefit. Why does Yahoo put out YUI, Hadoop, YTS for free? Why does Google give out protobufs, GWT for free? Why are there public tech talks at these companies? Can you quantify the benefit of such activities?