If we get down to the basics I think anything that is a medium of exchange is a currency. So in some circles cigarettes and Tide work as currency. Though these "currencies" are not legal tender.
A store of value is something you could accept in payment for work and hold on to.
A medium of exchange is something a shoemaker can use to obtain bread from a baker who doesn't want shoes.
A unit of account is something with a value stable enough that you can measure the value of arbitrary goods with it; like the Bloomberg article says, it's what enables a cheesemaker to put a price tag on cheese without forcing her to become a currency speculator.
Which of these functions does Bitcoin have?
It is just a 3-4 year old technology lets wait and watch how this plays out before writing it off completely.
Bitcoin has none of this; it appears to substitute the moral equivalent of a Yahoo stock message board.
Why? Now's the time to get in at the ground floor!