We all hate this. I for one never employ this tactic, I think its cheap and unfair. So as an update to my last post about the topic(which you can find here), I'd like to discuss a bit more about the subject as the cheese play has gotten a bit more difficult to deal with. First lets start with the maps this is more commonly used on and why:
Any map where only two players can spawn have a higher chance of this happening as the rusher already knows where you are at. Steppes of War is probably the most common as this map has close positions and big areas to hide that pesky Pylon. The key is taking out that Probe creating them and preventing him from escaping. If he manages to get a Cannon down, this is something I found out recently, if you put 3-4 workers attacking it while its warping in, they will destroy it before it becomes active.
Remember, Canon Rushes are for the most part All-ins, but lately the person doing the rush will block his ramp as to prevent you from coming and and destroying his economy. At this point you will need to focus down his pylons and make sure those probes go down first. No probes means no way of building more trouble, and a blocked entrance into his base means he cannot bring more probes in.
Once you have cleared him out you are already ahead as the majority of his economy has been devoted to knocking you off early, but don't rush into his line expecting victory as he can still hold his own against you, but his weakness is the immobility of his force. He will have not built a Cybernetics core yet so expect a force primarily of slow moving Zealots and stationary Canons. Whats the best way to mop this up? Drops into his mineral line. You need to bring in forces to put pressure on him as this is the point in which he is weakest. When you know you are about to mop up his buildings in your base, begin researching or building that structure that lets you transport units. The sooner the better.