Whether it is labeled apartheid or not, Palestinians are not granted equal rights in Israel. Recent developments indicate Israel has no intention of ever granting the Palestinians their own state. While the US must support Israel's right to exist, we also must support the Palestinians rights, either fully incorporated into Israel, or as a separate state unto itself. It seems our only leverage is financial. Suspend the payments (3 billion a year or 9 million a day) we send to Israel.
Wikipedia has an unbiased article on Israel and apartheid.
http://en.wikipedia.org/wiki/Israel_and_the_apartheid_analogy