current_virtual_library_name() is a relatively new function, so I'm possibly the first person to even think of it. Mostly just to see it I could - I already use the function to display/hide icons based on the current VL, so why not column values? Creating the read/unread VLs was a good opportunity to experiment.
I did some across an oddity though. The book list view is sorted, but not in book details.
Not a big issue, but curious as to what's going on seeing as there's no sorting going on in the template.