I am an MBA student at Wharton, used this forum quite a bit when I was an applicant, so here's a little giving back.
Process has been mentioned in subsequent posts - list gets to us early in the AM and calls will vary based on the person assigned to call you and let you know you were admitted. Last year everyone who was admitted got a call, this year I am not sure if they are handling it the same way. International calls are tricky because not everyone has Skype, so some people have to find time in the admissions office to make those calls.
A waitlist isn't the end of the world, but in my opinion, odds are not in your favor to get off of it. I know only of a couple people who were admitted of the WL in my class.
Goodluck!