Bug 29002 adds the ability to book items ahead of time. It works at the daily loan level, but stores hours with the intention of expanding it to support hourly bookings. We should expose these hourly bookings as an option to end users.
Hourly bookings would be extremely useful for us - if it doesn't complicate matters overly we'd also love the potential for 15-minute intervals as well. Just where things can sometimes be booked on the half-hour for example.