Information sharing has most definitely improved. One example is the Prism program, in which the FBI is responsible for data collection and then pipes it to the NSA. Not saying that is good for the country overall, but the agencies are definitely sharing more data.
That has nothing to do with DHS. As a result of the 9/11 Commission's recommendations, the Intelligence Reform and Terrorism Prevention Act of 2004 put the Office of the Director of National Intelligence "in charge" (in an oversight capability) of the 17 major intelligence agencies we have here in the US.
For better or worse it dramatically increased intelligence sharing and cooperation, as well as effectively tearing down the walls between domestic and foreign intelligence work.
