“Jambo?” (“How are you?) is usually said immediately prior to a handshake. Handshakes are required, regardless of how many people you are greeting. For example, if you enter a room with 30 people gathered for a meeting, it is usually expected that you will take the time to greet each individual with a handshake. Handshakes among friends can be almost comically effusive; old mamas will swing their arm from behind their body to smack and grab their friend’s hand in mid-air, amidst verbal greetings and laughter.

Source: http://guide.culturecrossing.net/basics_business_student_details.php?Id=7&CID=107