Khomeini was the guy exiled by the Shah/King of Iran that returned after the US coup (that turned into the Revolution). He's the guy that has made Iran an Islamic Republic and turned Iran into the voice of opposition to Israel's domestic policies and the US's international policies. It's pretty safe to consider him the founder of contemporary Iran.
We went to his shrine and got the diplomatic treatment. We were one of this first to get to go up into the 'call to prayer' towers. (Defintely the first tourists). They were all very nice to us and underscored their love for the American people (Though many of the mourners were taken aback to hear that we are American.)