Currency as Art?

Today was the first day of my Philosophy of Art course. We had a discussion about whether or not currency is art. I found this extremely interesting because I had never considered thinking of currency in the context of art. We all broke off into groups and discussed this. Later we came together as a whole class and our professor had us choose a if we felt it was or was not art; no middle-ground. I initially was going to argue "yes", but felt I was truly on the "not art" end of the spectrum.
I say this because before stepping into that classroom and having the thought of currency as art presented in front of me, I did not consider it as such. I do feel that the images on the currency, if taken out of the context of the currency, can be considered art and are art. However, if we are going to look at the currency as a whole and not separate entities, it is not art. The function and sole purpose of currency is to purchase goods. It was not created out of the need for aesthetics or the need to express an idea or display beauty. It was created as a way to distinquish between other countries and to also made it difficult to counterfeit.
That isn't to say the images on the currency do not convey any of these art qualities; it just wasn't the purpose and is not the function. If you take the images of the currency and place them entirely separate from the currency their function as a way to purchase goods ceases and you are left with art. This concept is comparable with the concept that you wouldn't say a truck is a piece of art. It may be beautiful or aesthetically pleasing, but it was created for the sole purpose of transportation. You don't just buy a truck to place out in your front yard like a statue on display, you purchase it so you can go places in a quick fashion.

Feel free to leave comments and your feelings on this subject. I'd love to know what everyone else thinks.