Medicine call at Duke is generally q4, and you leave in the late morning/early afternoon (max of 30 hrs on). There's a day float system so as to enable the post-call residents/interns to get home as early as possible. The day float residents round with the post-call team in the AM and basically take care of the discharges, SCUT, etc. that needs to get done, so the post-call team can go home and get some sleep. Gen med teams take "short call" as well, and get a maximum of 2 patients by noon (or 2pm depending on whether you're at Duke or the VA). Short call alternates with long call, such that if you're on long call on Monday, you're on short call on Wednesday, and then long call again on Friday. On gen med at the Durham VA you do NOT take call on Saturday; instead it's covered by a special resident-run service called PRIME, who admits the patients for you, and then gives them to the team that's on call on Sunday.
In the ICU I'm pretty sure call is q3, but I don't know exactly how it works as I haven't rotated through there.
I'm not sure about the peds side either, as there have been a number of changes in the past year or two. The department was experimenting with a night-float system a couple years back, but I believe they ultimately canned it because of the problem of multiple "handoffs," and the admitting teams often not knowing the patients all that well. I'm not sure what they ultimately chose to do.