At my school (University of Colorado - Boulder, Aerospace Engineering), the grade cutoffs are very much class dependent. I've gotten a B with an 88 before, but I've also gotten an A with a 76. It all depends on how the professor sets the curve (and what the averages are). An A+ doesn't exist here.
As for grade inflation? I have noticed in my graduate classes that an A seems substantially easier to get than it was in undergrad (I'm in the BS/MS program that allows for a masters in 5 years - last year, I was in both graduate and undergraduate classes). I was sure that I was going to get a B in fluid mechanics in the fall, but I ended up with a solid A. However, the requirements also went up - a C is no longer passing, so the only possible passing grades are A and B. While this has helped my GPA (I have a 4.0 in graduate courses so far, compared to a bit over 3.4 in undergrad), it also has the effect of reducing the resolution of the grading scale. Where before, an A took substantial effort and well above average performance, an A in graduate school so far seems to be relatively easy to get, and only require average or slightly better performance.