Apple's Maps have been a big disappointment. One important piece that's missing: transit directions.
HopStop does transit directions, which will greatly improve Apple's Maps.
This is the second mapping acquisition from Apple that's come to light in recent days.
Earlier, news broke that Apple bought Locationary, a sort of Wikipedia for maps.
Google's maps run circles around Apple's maps. Acquiring pieces like this is very important if Apple wants to be competitive with its maps app.