Those who call for boycott of and divestment from Israel generally call for an end to US aid to Israel as well.
The US government also supported successive apartheid regimes in South Africa (Cf. _South Africa and the United States: The Declassified History_, <http://www.gwu.edu/~nsarchiv/nsa/publications/DOC_readers/saread/saread.html>; _South Africa: The Making of U.S. Policy, 1962-1989_, <http://nsarchive.chadwyck.com/saintro.htm>), but I don't recall anyone holding up this fact as a reason that Americans shouldn't boycott and divest from South Africa, rather than as the reason for Americans to change US foreign policy toward it.
BTW, there exist more than similarities between Israel and apartheid South Africa. Israel actively supported apartheid in South Africa (Cf. Benjamin Beit-Hallahmi, _The Israeli Connection_; Jane Hunter, "Israel and South Africa," <http://www.thirdworldtraveler.com/Global_Secrets_Lies/Israel_SAfrica.html>; Jane Hunter, _The Israeli-South African-U.S. Alliance_, <http://www.ameu.org/uploads/vol19_issue1_1986.pdf>). -- Yoshie
* Calendar of Events in Columbus: <http://www.osu.edu/students/sif/calendar.html> * Anti-War Activist Resources: <http://www.osu.edu/students/sif/activist.html> * Student International Forum: <http://www.osu.edu/students/sif/> * Committee for Justice in Palestine: <http://www.osu.edu/students/CJP/>