It's a bit confusing to me too. As far as I understand, FedEx will deliver on Saturdays if the shipper pays for it, but I don't think they would pick up a delivery on Saturday and also ship it out that same day. I could be wrong, though.
Even so, there's definitely no Sunday service, right? Or does FedEx operate 7 days a week, but just not do deliveries on Sundays or Saturdays (except when Sat. delivery is chosen)?
I think it means that Wirefly requested the overnight delivery from Sprint, so that Wirefly gets the phones shipped to their facility overnight, not that they're doing overnight delivery from Wirefly to customers over the weekend.
On a separate note, when I cancelled my Wirefly pre-order, I was told they can re-open my order anytime within 30 days of canceling. So, just thought I'd share that info.