Hi Ryan,
I'm tinkering at the moment, and I seem to be able to sort on picklist values normally unless the picklist is ALSO a multi-select type. Those definitely have greater limitations, I'd suspect the data is stored in such a way that it would make it hard to add those extra features. So first - is the picklist you're referencing one that allows multiple choices?
If so, does it have to be? Could you make it two lists that required one choice each? You could potentially recombine them in reporting if you wanted to display that way.
If it needs to remain a multi-select, is the list small enough that creating another set of fields that populate based on those choices a viable option? IE if you have 6 people listed, then it would be possible albeit annoying to create another set of fields that change depending on what's selected in the original picklist. Those fields could then be used in reporting to sort on.
The second option is viable if the number of choices is limited and relatively static. If it's long or highly variable, then you may be setting yourself up for a maintenance nightmare.
Katherine