The battery/concrete thing comes from back when batteries were still made witha rubber case and tar sealed tops. The way I was told was that the rubber case didn't insulate the battery from condesation very well, and sitting on cold concrete caused accellerated condensation which would drain the battery by diluting the acid. It could also cause cracks to form in the casing.
Modern batteries are made with a polyethelyne plastic case. They are not suceptible to the problems that the old style batteries were.
Still, if you can put it on a shelf or workbench, that would be preferred to leaving it on the floor (ever trip on a battery? Not fun.).
If the truck is going to be sitting for an extended period, a maintainer is a good idea. The flaps or farm store will have them. Sears also has them in their auto centers.
