Power Line has video and details. Here's an excerpt from the L.A. Times (no link because the Times site pointers seem busted):

Jim Gilchrist, the Aliso Viejo accountant who co-founded the Minuteman Project, was forced offstage seconds into his speech at Columbia University on Wednesday night by students who said his anti-illegal immigration message was not welcome in New York.

Gilchrist, who was invited by the Columbia University College Republicans, was unharmed but was unable to continue speaking as planned and was forced to leave the stage after an altercation with students....

The Columbia melee began after two students rushed from behind the stage toward Gilchrist and unrolled a banner that read in Spanish, English and Arabic, "No One Is Illegal."

Seeing the two, others in the audience ran toward the stage, including about two dozen who managed to get onto the 3-foot-high platform, past security guards and ropes, where Gilchrist was only a few words into his speech.

The lectern was knocked over and Gilchrist fell back, smashing his reading glasses....

No one was arrested. The incident was videotaped and shown on TV newscasts....

Oh, and here's a lovely quote from one of the "protest" participants, Columbia junior Ryan Fukumori (a board member of the Columbia Asian American Alliance and treasurer of the Columbia International Socialist Organization:

These are racist individuals heading a project that terrorizes immigrants on the U.S.-Mexican border .... They have no right to be able to speak here.