From *Daily Waqt* - published from Lahore, Sunday August 31, 2008:
Lahore (Pervez Al-Islam): The mother of American Presidential hopeful, Barack Obama, Mrs. Ann Dunham lived in Pakistan for five years. During this time, Barack Obama also visited his mother and stayed for a few month. Mrs. Ann Dunham was hired as a consultant by the Asian Development Bank for Pakistan Agricultural Development Bank's Gujranwalla Agricultural Development Program. This program began in 1987 and ended in 1992. Mrs. Ann Dunham monitored the funds received for this program from the Asian Development Bank and trained the Mobile Credit Officers of the Agricultural Bank. This program was controlled from the Gujranwalla Regional Office. She stayed for five years in the Hilton International Hotel (now Avari Hotel), Lahore. She travelled daily from Lahore to Gujranwalla. When Barack Obama visited Pakistan, he stayed in the same hotel. After returning from Pakistan, she died from cancer within three years.
I have read that he visited Karachi in early nineties to visit his college mate (someone called Chandio) but there was no mention of Lahore. Obama apparently comes up with something new all the time