I know as much about Minecraft as the next person with children who play - which is to say quite a LOT without having used it myself. It seems to me a great medium for creative, cooperative and safe online recreation and a good fit for a library environment (with the right management and controls).
Twitter provided three examples, the first two via @edwardshaddow and the third via @tamavisions
[City of Stonnington, Prahran library has Minecraft on Xbox360]
Is this a good idea for a public library? Do you have other examples to share?