The Times Economix blog reports on a study of grade inflation since 1960 by Rojstaczer and Healy, and even shows a nifty graph of grading densities over time. Wow!
My own record at Queens College, a public institution? Since 2006, 25% A's, 40% B's, 24% C's, 5% D's, and 6% F's. According to the graph, I'm pretty much lined up with the "1980 Public" density.