library(ggplot2)
my_title = \"This is a really long title of a plot that I want to nicely wrap \\n and fit onto the plot without having to manually add the backslas
I do not think there is a text wrap option in ggplot2 (I have always just inserted \n manually). You can, however, shrink the size of the title's text by altering your code in the following way:
title.size<-10
r + geom_smooth() + opts(title = my_title,plot.title=theme_text(size=title.size))
In fact, you all aspects of text with the theme_text function.