The Last Day, the second minisode preceding The Day of the Doctor, is now out on iTunes. For some reason it's free in the US but is not free in the UK.
My verdict: It's interesting, but it's not mindblowing as The Night of the Doctor was. It's standard prequel minisode fare - enjoyable, but horribly predictable. It did, however, give us a glimpse at something we'll probably be seeing more of in the special itself: The Fall of Arcadia.