title: Text labels for ggplot2 facet_wrap
body: <p>I am having trouble putting letter labels on a facet_wrapped ggplot2 graph.  It should be simple and I have done it before... although obviously I am not doing something right at the moment. The letters are just plotting atop one another in every plot when there should be a different letter in each plot.  Has something changed recently or am I overlooking the obvious?</p>
  
  <pre><code>library(ggplot2)
  library(reshape2)
  posdat&lt;-data.frame(  x=c(rep(10,4)),
                       y=c(rep(0.4,4)),     
                     lab=c("A","B","C","D"),
                      stringsAsFactors = FALSE)
  sp &lt;- ggplot(tips, aes(x=total_bill, y=tip/total_bill)) + geom_point(shape=1)
  sp+geom_text(data=posdat, aes(x=10, y=0.4, label=lab))+
  facet_wrap( ~ day, ncol=2)
  </code></pre>