There are two key current books for general audiences covering Kenya’s post-independence history and I recommend both.
The more comprehensive is Charles Hornsby’s Kenya: A History Since Independence which I read a few months ago. Charles brings the advantages of both scholarly training and deep personal experience including several years living in Kenya and much prior research and writing and “Kenya watching”, while at same time offers the independence that comes from earning his living separately, presently as a corporate compliance official. Hornsby’s book is over 900 pages of deep detail including significant attention to economic policy and the business history that is so essentially a part of Kenya’s politics. Hornsby’s work will give the basic background on the past interactions and alignments of most of Kenya’s current political figures during the Jomo Kenyatta, Moi and Kibaki years.
Historian Daniel Branch’s Kenya: Between Hope and Despair is also excellent and it is the book I recommended for a quick primer for a friend who was considering a short term election-related assignment in Kenya in late 2012. At just under 400 pages it is a much quicker read and will well serve the needs of the shorter term generalist for a tighter summary of the key events; along with the crucial Chapter 12 (titled “Back to the Future”) of Hornsby’s history–with the best detailed summary I’ve read of the vital 2007 campaign and election–Branch’s book will give general readers some understanding of the lay of the land in public affairs in Kenya in a few short hours.