In case someone missed this link that Ansar posted, I'll paste part of it.
Shaking hands is a Sunnah. However it is not a formal act of worship like prayer and fasting that must be performed in a specific way. Therefore, the question of innovation does not come into play here. We believe that the manner of shaking hands is something to be done according to customs of the people.
It is well-known that in some eastern societies, when someone uses two hands in welcoming his counterpart, it is an indication of affection towards him. In some parts of the Arab world, it is customary to greet a person by placing the left hand on the other person’s elbow when shaking his hand. In parts of the Sudan, it is the custom to first place one’s hand on his counterpart’s shoulder before taking his hand.
The important thing is to greet your brother with “salâm” and to shake his hand.