I have found that in any worlds created in 1.8.2 -pre2 and -pre3 the hoppers do not transfer items to another hopper or into a chest/furnace/whatever. The hoppers worked fine in 1.8.1 and 1.8.2 -pre1.

I have not tried to see if the hoppers work in a world created before 1.8.2-pre2 opened in -pre 2 or -pre 3