There is an old version of the Linux kernel on the pSPT. Why was the 2.6.27 Linux kernel chosen instead of the latest kernel release series?
The pSPT development team is using this kernel because it has been dubbed the long term supported (LTS) kernel. See this for details. This particular kernel lineage will still receive all of the benefits from kernel development (device drivers, security patches) but will not be subject to the same bleeding edge development that the newer (and frequently forked) head of the development effort will receive. This choice makes for a stable kernel that should be free of any defects introduced by new development.