A colleague has a family story that if confronted by a skunk, if you can get its rear feet off the ground, it's unable to release its foul-smelling spray.
Evidence for or to the contrary?
I found a couple of sources indicating that skunks can spray with their feet off the ground:
Skunk Fact Sheet from the Georgia Department of Natural Resources:
Dealing with Skunks, produced by the University of Nebraska:
I would consider them reliable. Both are produced by reputable organizations that deal directly with wildlife. This isn't a very hard thing to ascertain, since all you need is one counterexample.
If you search the internet, you will also find lots of anecdotal evidence of people personally attesting that they have been sprayed by skunks in just such a position. These sources may not meet the evidence standards of this site, but they are definitely enough to stop me from picking up a skunk.
Incidentally, an acquaintance of our family believed a related myth: "a skunk can't spray in a trap because it can't put its tail up." He personally discovered that this was untrue.