For lengthy prose copy (such as in an ad, or sidebar text shaped purely for effect in a layout), pasting into a shaped frame in Illustrator or InDesign is usual, as lawndartcatcher has indicated. In such a case the copy often must be edited to fit the space available, however. For a short song segment or poem it makes much more sense to simply choose appropriate line breaks to achieve the effect you're looking for. You don't need special software.
This type of poetic conceit traditionally uses straight typography and the writer's choice of line breaks. The desired shape also influences word choice in such a case. (The mouse's tale/tail in "Alice in Wonderland" is something of an exception, but that merely adds to the humor. Note, however, that it was originally set in metal type, without benefit of software.)