SparcLinux (ok, ok, Sparc is (tm) Sun, so it's really S/Linux. Whatever.) is linux ported to the SPARC microprocessor based systems, specifically to Sun SPARCstations. This is not a "new" version of Linux, it is a port that is integrated into the normal distribution kernel tree. The user level interface and most of the kernel is still the same. Only machine-dependent parts of the kernel have changed.
See the SparcLinux homepage: http://www.ultralinux.org/