It is a very common finding, and only rarely produces symptoms.
These symptoms can be bleeding, or if one of the pockets becomes infected or damaged, fever, pain, diarrhoea and other infective symptoms. Infection of a diverticulum (or pocket) is called diverticulitis.
The Colorectal Surgical Society of Australia and New Zealand (CSSANZ) has produced a leaflet summarising some information on Diverticular disease.
If you are worried about your symptoms you should talk to a doctor.