I had never heard this term, but I like it. From an interview in Solid State Technology with Margaret Blohm, Chief Scientist and Leader of Nanotechnology at GE Global Research, emphasis mine:

Q: What challenges do you face in managing nanotechnology research programs and scientists?
The challenge of dealing with a lot of enthusiasm and making sure we stay on track with business impact and not just really cool technology. It can be hard on folks who have a good idea that’s not ready for a specific business use. An even bigger challenge is doing matrix managing. I’ve never been a fan, but I love it now. Matrix managing is the process of influencing organizations or departments or other structures where you don’t have individuals directly reporting to you, to help them recognize the mutual benefit of what they are working on.
I matrix manage the people on the various research teams. I reach in to their team and work with them. For example, a chemist is on one team and can join my team as well. It’s usually a management nightmare, but it has worked here. It’s communication both ways. They aren’t isolated from business challenges and opportunities. Matrixing helps do that.