I should start this post by first saying that i own a macbook and not a macbook air. However i do live 10 minutes away from an Apple store (Japan) and often play with other models. I have used the trackpad on every one of the macbook air display models in the local store and if i run my finger down the touchpad in a straight line as i might on my computer the cursor jumps randomly from side to side. going a few millimetres down the line and then jumping up to a few centimetres to the right or left. if i do it a few times i can get it to work slightly better (by using the side of the trackpad instead of the middle) but its still well out of what id call a usable experience. i have tried at least 3 macbook airs and the behavior is the same in all of them while my friend has perfect control over the same machines (as youd expect). the best possible way i can make an absolutely straight line is buy using the back of my knuckle. I have been to the store on different days, once wearing gloves (winter) and again recently when the weather is much more spring like. its behavior was the same. im wondering what people around here think it might be. Ive worn different fabrics including wool and plain cotton so id be surprised if it were the effect of static electricity. i do have warm hands (cold heart?) compared to my friend but not unusually so. i do not wear jewelry or pick my nose and as is the custom in Japan i keep my hands relatively clean. anyone out there keen to take a guess whats going on here?