This article was originally taken from: http://en.wikipedia.org/wiki/Zabuton
A zabuton (座布団) is a Japanese cushion for sitting. The zabuton is the everyday cushion found in homes and used for eating, watching television, reading at the kotatsu, and other daily activities. A typical square zabuton measures 50–70 cm (20–30 inches) on a side and is several centimeters thick when new.
Zabuton are found throughout Japan, and enter many aspects of the culture.
In Zen, practitioners sit on zabuton when meditating.
In sumo, members of the audience throw zabuton toward the ring after an upset.
During a Chaji the host might bring out zabutons for the guests during the break between gozumi (if any) and usucha. The host should first bring in the one for the shokyaku then for all the rest in a pile.
During a Chakai some or all of the guest might get zabutons. If only some guest gets it is a statement about their importance. So during Keiko a teacher might be given one.