If you look at April '11 Revenue the Total Revenue for the 52 weeks prior is for April '10 instead of the actual days displayed 4/2/10 - 5/1/10. This does seem logical, if I want month over month sales I will look at April '10, for this report I'm specifically looking for that 52 week comparison.
My recommendation is for Site Catalyst to show the Total Revenue for the period that is displayed.