You would think that the topic of the Israeli security wall on its borders is passé, but the people at Procon.org decided it was important enough to resurrect the debate, so I might as well give a brief overview.
Why build a fence in the first place? A fence either keeps people in, such as a prison fence, or it is meant to keep people out. In this instance, Israel built a wall because of the latter, because they wanted to bring an end to the huge amount of terrorist attacks that were occurring back in the early 2000s under the Arafat regime. The result? A huge reduction in terrorist attacks. The construction had absolutely nothing to do with oppression and everything to do with a legitimate security concern. But that never stopped the United Nations from giving Israel a hard time, not that I actually care what the United Nations think....might have something to do with their anti-Israel bias.
Let's get back to the fundamental question: does a security fence bring peace? No. It brings about security. That is its function, and it has done quite a nice job at succeeding. Do you think that there is going to be peace between the Israelis and Palestinians if they took down that fence today? Of course not! Because much like the land disputes, it's not the root issue. As Golda Meir put it, it's because the Palestinians hate the Jews more than they love their own children. Not even the "moderate" Fatah recognizes Israel's existence. If you can't even recognize Israel's existence, how can you even begin a peace process? You don't make peace with your enemies; you make peace with your former enemies. When hatred for Israel stops being a Palestinian norm, then there will be hope for peace. But until such an event takes place, Israel might as well protect its citizens while this stalemate is perpetuated.