Does a rear wheel work up front?
Most bikes use 100mm in the front and 130/135mm in the back, so its unlikely it would fit unless you knew a priori that your bike was one that could have it fit. 

However, some bikes are designed for running rear hubs in the front (Surly Moonlander/Pugsley, for example).

A non-Fat Bike case is the Salsa Enabler.