They are not very widespread but, they are actually very good SPARC workstations.
SparcBook 1:
SparcBook 2:
Tadpole SparcBook 3GX:
This is a 100Mhz MicroSPARC II (TI) with a Weitek P9100 frame buffer and a screen resolution of 800x600.
GNU/Linux runs on it
The PCMCIA, internal modem and power management are not supported at the time
of this writing.
Nextcomputing:
http://www.nextcomputing.com
At least one of their laptops, the NextBlade 150 is advertised as being
capable to run both
Solaris and the RedHat GNU/Linux.