What Meryl said. Of course, assassinating Arafat isn’t necessarily the most practical option; we could always arrest him, since the U.S. has evidence of Arafat ordering the murder of U.S. diplomats in the early 1970s, when (I could be wrong about this) the U.S. didn’t grant him any special diplomatic status.
The Bush Administration, of course, will do no such thing, and for reasons of the larger picture, that’s probably for the best. But for Israel, not so much.