Arnd Bergmann is the maintainer for the Cell Broadband Engine platform in the Linux kernel. Aside from working on that platform he has contributed to a variety of subsystems in the kernel over the last years. He has been working at the IBM Linux Technology Center as a kernel hacker since 2002, where he started in the s390 architecture team.
An increasing number of Linux based machines features PCI express ports that can be used as an endpoint instead of a PCI express root complex. Examples include the "Triblade" of the LANL Roadrunner supercomputer, embedded Linux based PCIe cards and blade servers with a switched PCIe backplane.
So far, there is no common infrastructure for this and device drivers are largely incompatible. On the way to a generic code base, we are looking at virtual device driver (virtio) providers on top of PCIe, implementation of Message Passing Interface (MPI), and possible user interfaces for setting up the devices.