sa·laam (s-läm)
n.
1. A ceremonious act of deference or obeisance, especially a low bow performed while placing the right palm on the forehead.
2. A respectful ceremonial greeting performed especially in Islamic countries.
tr. & intr.v. sa·laamed, sa·laam·ing, sa·laams
To greet with or perform a salaam.
[Arabic salm, peace, salaam, from salima, to be safe; see lm in Semitic roots.]
http://www.thefreedictionary.com/salaam
Does that mean obama should have put his own hand on his forehead or what when he performed the low bow?