We're running out of hops... well, at least until the next harvest comes through. In fact, that's not entirely true, we're just about managing to keep up our stocks by searching the market place at length. Recently East Kent Goldings, a staple English hop, became unobtainable but we've got that back in stock now.
The cause of the shortage is craft beer consumption. Hop producers are struggling to supply the demand. Craft beers are nearly all, without exception, incredibly hoppy in taste. This extremely hoppy characteristic is created, unsurprisingly, by using many more hops in the brewing process than traditional beer recipes require - generally speaking. The USA is at the heart of the craft beer revolution, you can read more about the hop shortage statistics here on the drink business website.
The technique of dry-hopping is one of the key processes responsible for the hop shortage. Read about various methods of dry hopping here.