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.