I just wanted to bring some attention to the experimental build of CentOS that Pasi put together for sparc64 architecture. I installed it for the first time last night on a Sun Ultra 5 (333MHz, 256MB RAM, upgraded to 40GB hard disk).
I installed it over a serial console as this is a headless system. Install went flawlessly. After the install was done and it booted up, I ssh'd in as root, and within 5 minutes had it participating in my LDAP/Kerberos/NFS environment. Logged out, logged back in with my regular user account with X11 forwarding enabled, and started firing up GUI apps.
The box is a little memory starved, and I think with 512MB it would be a lot better, but it is quite usable! App startup time is longer than what my Athlon64 3700+ has me accustomed to but once the apps are running, they are snappy & stable.
If you have an old 64 bit Sun workstation kicking around collecting dust, I think it would be worthwhile to try this build out and post your results to Pasi's centos-sparc mailing list. With any luck, maybe we can get to the point where this is an officially supported architecture.
Some apps are still missing, as is to be expected with a new architecture. Most notably, OpenOffice.org is not there. I did run firefox, gimp, thunderbird, and xchat flawlessly though. I can't comment at all on local X11 console support because my sun boxes run headless.
This is inspiring me to save up for a loaded Sun E420R or E450 to run at home and replace my Duron-based web/mail server.