!!! NOTICE !!!
Not all code in the ROS ecosystem has been released under BSD or similarly permissive licenses. The default license created by roscreate-pkg is "BSD" but some people do not know or do not care what this means, and they can be careless with the code they use or link against in that package.
If you are concerned about licensing, make sure that the contents of the package and all of its dependencies are also covered under the appropriate license for your application.
The answer for the ROS core, however, is YES. In fact, the entire motivation for pushing that the ROS core and most of the mantle is BSD-licensed is to enable commercialization of ROS-based robots. You can even build and sell proprietary software built on top of BSD-licensed code.
Also it might be useful to link people to the ROS developer's guide, which goes over some of these issues.