Does the performance of the MAC MINI justify the price, when compares to a proper rack server ?
As far as I know Apple products are known for being overpriced, the whole project looks more like a concept rather than something practical.
Because you can do things on a mac that you cannot do on 'easily' other hardware...
Let's say for example you are running Xcode, macs have the ability to run as a 'farm' service, that is to say that if you have a corporate network with macs, each and every one is able to share the processing power of the others and it is built right into the applications.
Just plug the shit together, its all automatic.