\documentclass[11pt]{article}
\usepackage{verbatim}
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\usepackage{url}
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\begin{document} 
\paragraph{R users:}

Suppose you have a table (or matrix or dataframe) with a lot of text in a cell, such as the following. 
<<defineStuff, echo=TRUE>>=
bigmess<- 
data.frame(
animal=c("I have done the state some service and they know it. No more of that. I pray you, in your letters, When you shall these unlucky deeds relate, Speak of me as I am. Nothing extenuate, Nor set down aught in malice."
, "Elephant" , "primate", "puma")
, x=sample(1:199, size=4, replace=FALSE))
bigmess$why<- rep("Aye", nrow(bigmess))
# Note that bigmess has three variables (columns):
names(bigmess)
@
If you print it out ``naïvely'' using xtable and Sweave, the table marches off your page and you don't even see all of the first column:
<<fizz, echo=TRUE, results=tex>>=
tmess<-xtable(as.matrix( bigmess))
print(tmess, include.rownames=FALSE)
@
You could convert 
\texttt{bigmess} to a spreadsheet format such as Excel\textregistered{};
then you could highlight the "animal" column and specify ``wrap text.''

But suppose you prefer to do this in a reproducible way in R. 
Try the following. 
<<fEE, echo=TRUE, results=tex>>=
align(tmess) <- c("r", "p{1.5in}", "c", "c")
print(tmess, include.rownames=FALSE)
@
\begin{verbatim}
Sweave("foo.Rnw")
texi2dvi("foo.tex", pdf = TRUE)
\end{verbatim}
Jacob Wegelin \linebreak{}
Thanks to
\scriptsize{}
\url{http://stackoverflow.com/questions/2686320/how-to-put-a-newline-into-a-column-header-in-an-xtable-in-r/2687142#2687142}.
\normalsize{}
% Sweave("foo.Rnw")
% texi2dvi("foo.tex", pdf = TRUE)
\end{document}