on an ultra (ultra1.test.redhat.com) running lpr w/the default printer connected locally hangs the machine, requiring a reboot ... running lpr with the printer configured for local access but not physically attached does NOT hang the machine... this was tested with lpr-0.48-1.sparc.rpm lpr-0.46-1.sparc.rpm
Since it hangs the machine it's probably a kernel issue... And we don't have a sparc over at redhat.de, so I can't do anything to reproduce this/trace it down.
It's a kernel bug, should be fixed in 2.2.15preX.
... which will be in the next Raw Hide release.