I don't think it's a coincidence that my back has started to hurt a lot more in the last few months as well. This is especially true for the upper right side of my back, which I believe is strained from using a mouse over a long period of time (I'm right handed).
So, I started doing weight lifting again and already things are feeling better. Unfortunately, I've developed some muscle knots the size of Kansas in the meantime and I'm not sure if those will work themselves out. I'm taking creatine and betagen to help with muscle recovery - not sure it will help with the knots.
I've also started using some backache cream, which is just a menthol substance that seems to help some. Oh, and a little safety tip for you men out there - after applying any sort of back cream, be sure to wash your hands *really well* before going to the bathroom - ouch!