The OCERA Project has released LinCAN 0.2:
an implementation of the Linux device driver supporting more CAN controller chips and many CAN interface boards. The driver roots can be traced to LDDK project. The OCERA version of the LinCAN driver adds new features, continuous enhancements and reimplementation of structure of the driver. The usage of the driver is tightly coupled to the virtual CAN API interface component which hides driver low level interface to the application programmers. Driver enables multiple opens of each communication objects from more Linux and RT-Linux applications. The message processing is based on the oriented graph of FIFOs concept.
CAN is a really interesting protocol, but the last time I was at a real-time/embedded trade show, it appeared to be a pretty closed environment. LinCAN will at least let you use CAN-specific hardware in an embedded Linux.