Here's a look at the NFL Combine Schedule for Friday. Defensive linemen and linebackers (including Pitt's Chas Alecxih and Brandon Lindsey; Penn State's Devon Still, Nate Stupar, and Jack Crawford; and West Virginia's Bruce Irvin and Najee Goode) will arrive in Indianapolis and will have x-rays, orientation, and interviews.
Meanwhile, quarterbacks, running backs and wide receivers will have medical exams, psychological tests and measurements. Placekickers and special teams players will have a workout.
The workouts will really begin in earnest on Saturday, when the offensive linemen start drills. The Steelers will surely be paying attention there, since they need plenty of help at the guard position in particular. Defensive linemen and linebackers work out on Monday, and that will be a crucial day for the Steelers as well -- they're also looking for help at nose tackle and middle linebacker.
A full combine schedule is available here. And here's a full invite list.
For more on the NFL Scouting Combine and the NFL Draft, check out Mocking The Draft. For more on the Steelers, there's Behind The Steel Curtain.