Wow Joe, thanks as always for the quick work! While checking out your fix, I just happened to notice a few other small issues with CSS classes. On the demo site, the event on Sunday the fifth is being rendered with a class of "mpcalendarday" instead of "mpcalendarweekendday" as the one on Saturday the 11th is.
I think the event on "today" should be rendering with a class of "mpcalendartoday" instead of "mpcalendarday", and events being shown in other months (for example 11/30) should be rendering with a class of "mpcalendarothermonth" instead of "mpcalendarday".
These discrepancies are causing the event background colors to be slightly off when you look closely at them.
Jamie