As a protoss player, walling your ramp with two buildings and a zealot is pretty standard in ZvP. Every zerg player has experienced the frustration of being unable to bypass the hold position zealot. However, I have played several games over the last month where my zerglings were able to slip by for some reason. At first I attributed it to poor zealot position, but later I discovered that there is actually a way to force zerglings past the hold position zealot. It is very simple too:
1. Get a group of zerglings
2. Run them up the ramp and spam click right next to the zealot. Sometimes this can be hard to do because of various building positions, but you can still do it.
3. Your zerglings will push the zealot out of the way and eventually you can stream lings past and wreak havoc in the base.
Unfortunately, I think this sort of breaks the ZvP matchup =/. The other races can't handle a swarm of zerglings that early on inside their base, so they sort of need that wall. The only counter to this is to make a complete wall with a pylon or something.
Here is the replay:
I did it twice. The first test had a zealot with one side to the cliff and one to the building, and the second was with the zealot between two buildings. It is much easier to do this when the zealot has a cliff to his side.