Depending on who you talk to and where you listen, the Lean and TOC communities are either close partners or opposing players in the "continuous improvement" arena. But from my perspective they are much closer to being friendly than opponents.
I listened to Mark Graban's Leanblog podcast #263 with Pascal Dennis over the weekend, and it really highlights many of the similarities in approach and underlying belief system from people who use Lean concepts and those who use Theory of Constraints concepts. They don't discuss this connection directly, it was just the ideas really resonated for me.
I particularly liked a number of comments that Pascal had around the purpose and intent behind Lean. Specifically, the general approach behind continuous improvement efforts is NOT about cutting costs. It's about creating value and ensuring flow (the better things flow, the sooner the value comes). Sometimes lower costs are an outcome of these efforts, but that is not the focus.
There were many other comments that resonated for me throughout the conversation, such as management's role in any such approach. It isn't "set it and forget it" or "tell them what to do" - abandoning people to figure it out for themselves. Lean and TOC and other methodologies must be much more about learning and listening. This gets organizations much closer to real "empowerment."