Disneyland does something like this with wait times for attractions.

According to a 1989 Newsweek article: The waiting times posted by each attraction are generously overestimated, so that one comes away mysteriously grateful for having hung around 20 minutes for a 58-second twirl in the Alice in Wonderland teacups.

Source: http://dspace.mit.edu/bitstream/handle/1721.1/37703/21793670...