Hello. I'm the admissions chair at a top 50 (but not top 20) physics graduate school. I wonder if you are aware that some admissions professors do read this forum from time to time. It's quite interesting. Of course, some people do list the schools that they've been accepted to, and the stats are enough for admissions people to identify them---but it doesn't really matter much (I wouldn't try to identify anyone).
Don't be discouraged if you haven't heard from place X yet. I think every place puts every application into groups. For us, it's "accept immediately", "hold for a while", "reject". The problem is that if you want, say, 20 students in the entering class, and every applicant gets accepted by 4-5 places, then you would need to admit 80 or more. But then if you happen to get 40% acceptance rate, you get over 32 people (and at $20-$25K a pop, that's very expensive). So we always admit (if we want 20 people) only about 40, and then add more as the season goes on. So don't worry.
Some places send letters, some e-mail, and some make personal phone calls. Some have "admitted students days" , and some invite students one-by-one (usually smaller schools can do one-by-one, especially user-friendly institutions).
One desperate plea. If you get accepted into a place that is definitely higher on your list than place X, please e-mail place X and either decline (if you've been accepted) or withdraw (if you haven't heard). It then lets place X, often, make another offer right away, perhaps to someone on this forum. Believe me, we won't feel bad, and will appreciate hearing. There's nothing more frustrating than to have lots of good students on the waiting list, and having people who have been accepted holding lots of offers. And it's even worse to spend hundreds of dollars to pay for their visit when they don't really plan to come anyway. So please be courteous to your fellow students. Of course, you may not be certain which of two or more places you prefer until you visit....
Enjoy the rest of the season.