OpenBSD/sparc 2.1 is brought to you by the same people who did the first
free BSD port (based on Chris Torek's 4.4BSD work).  Many more sparc
models and devices are now supported.
In addition to the SunOS 4.1 compatibility, OpenBSD 2.1 will also run some
number of SunOS 5 (SVR4) executables in binary emulation mode.