Interdisciplinary teaching is the term used to describe when a curriculum focuses on a specific theme or project and aims to teach a variety of academic disciplines around that theme.  It seems to be a popular and trendy method–many schools I have visited use it and make a point to parents that they use it.  In my school research experience, the first school where I heard about it was the Waldorf School of Philadelphia, but I have heard school officials mention it at many other schools, public, charter, and private.  For example, Wissahickon Charter School uses this pedagogical method, and they give a good example on their website

Often, the central topics we choose are “terrains”-whole environments where social studies and science and math and literacy are still connected. Many of these studies are related to the nearby Wissahickon Valley and its watershed, but others are connected to the urban environment. So, for example, in one such study, a second grade does a comparative study of a supermarket and the local food co-op. Students go to both of these locales to buy lunch and then trace the origin of all the food that made up their lunches. It is a study that draws on the science related to nutrition; the environmental studies related to the pollution created in making and transporting the food; the social studies of production and the organization of work; the geography of local trip to the stores and the global path of the food; the mathematics and economics of pricing; and the literacy skills necessary for researching all of the above.

What are the benefits or pitfalls of an interdisciplinary curriculum?

Harvard Professor Howard Gardener is most famous for his theory multiple intelligences, upon which interdisciplinary teaching is based.  From Wikipedia,

Gardner argues that the concept of intelligence as traditionally defined in psychometrics (IQ tests) does not sufficiently describe the wide variety of cognitive abilities humans display.   For example, the theory states that a child who learns to multiply easily is not necessarily more intelligent than a child who has stronger skills in another kind of intelligence. The child who takes more time to master simple multiplication 1) may best learn to multiply through a different approach, 2) may excel in a field outside of mathematics, or 3) may even be looking at and understand the multiplication process at a fundamentally deeper level. Such a fundamentally deeper understanding can result in what looks like slowness and can hide a mathematical intelligence potentially higher than that of a child who quickly memorizes the multiplication table despite a less detailed understanding of the process of multiplication.

I am not expert in pedagogical methods, but this teaching approach makes intuitive sense to me.  However, I can imagine some situations where it may be a stretch to incorporate certain disciplines into a larger cohesive curricular unit.  What is more interesting to me is that the presence of an interdisciplinary curriculum must require that teachers are communicating and are on the ball enough to coordinate their efforts with one another.  My intuition tells me that schools that employ this approach must have a good system of communication between teachers and strong leadership.  I imagine that those channels of communication can pay dividends when situations arise with individual students.  It also just suggests to me that a school administration has a strong vision and is on the ball to be able to coordinate these efforts.  That is not to say that schools that do not have good communication or vision, but evidence of that would have to be found elsewhere.