The output of the 'summary()' function will not work with xtable.
However, the parameterEstimates() function returns a data.frame, which
is supported by xtable. This works rather well:
> library(lavaan)
> library(xtable)
> example(> xtable(parameterEstimates(fit))
% latex table generated in R 2.15.1 by xtable 1.7-0 package
% Wed Nov 7 21:24:00 2012
\begin{table}[ht]
\begin{center}
\begin{tabular}{rlllrrrrrr}
\hline
& lhs & op & rhs & est & se & z & pvalue & ci.lower & ci.upper \\
\hline
1 & visual & =\~{} & x1 & 1.00 & 0.00 & & & 1.00 & 1.00 \\
2 & visual & =\~{} & x2 & 0.55 & 0.10 & 5.55 & 0.00 & 0.36 & 0.75 \\
3 & visual & =\~{} & x3 & 0.73 & 0.11 & 6.68 & 0.00 & 0.52 & 0.94 \\
4 & textual & =\~{} & x4 & 1.00 & 0.00 & & & 1.00 & 1.00 \\
5 & textual & =\~{} & x5 & 1.11 & 0.07 & 17.01 & 0.00 & 0.98 & 1.24 \\
6 & textual & =\~{} & x6 & 0.93 & 0.06 & 16.70 & 0.00 & 0.82 & 1.03 \\
7 & speed & =\~{} & x7 & 1.00 & 0.00 & & & 1.00 & 1.00 \\
8 & speed & =\~{} & x8 & 1.18 & 0.16 & 7.15 & 0.00 & 0.86 & 1.50 \\
9 & speed & =\~{} & x9 & 1.08 & 0.15 & 7.15 & 0.00 & 0.79 & 1.38 \\
10 & x1 & \~{}\~{} & x1 & 0.55 & 0.11 & 4.83 & 0.00 & 0.33 & 0.77 \\
11 & x2 & \~{}\~{} & x2 & 1.13 & 0.10 & 11.15 & 0.00 & 0.93 & 1.33 \\
12 & x3 & \~{}\~{} & x3 & 0.84 & 0.09 & 9.32 & 0.00 & 0.67 & 1.02 \\
13 & x4 & \~{}\~{} & x4 & 0.37 & 0.05 & 7.78 & 0.00 & 0.28 & 0.46 \\
14 & x5 & \~{}\~{} & x5 & 0.45 & 0.06 & 7.64 & 0.00 & 0.33 & 0.56 \\
15 & x6 & \~{}\~{} & x6 & 0.36 & 0.04 & 8.28 & 0.00 & 0.27 & 0.44 \\
16 & x7 & \~{}\~{} & x7 & 0.80 & 0.08 & 9.82 & 0.00 & 0.64 & 0.96 \\
17 & x8 & \~{}\~{} & x8 & 0.49 & 0.07 & 6.57 & 0.00 & 0.34 & 0.63 \\
18 & x9 & \~{}\~{} & x9 & 0.57 & 0.07 & 8.00 & 0.00 & 0.43 & 0.70 \\
19 & visual & \~{}\~{} & visual & 0.81 & 0.15 & 5.56 & 0.00 & 0.52 &
1.09 \\
20 & textual & \~{}\~{} & textual & 0.98 & 0.11 & 8.74 & 0.00 & 0.76
& 1.20 \\
21 & speed & \~{}\~{} & speed & 0.38 & 0.09 & 4.45 & 0.00 & 0.21 &
0.55 \\
22 & visual & \~{}\~{} & textual & 0.41 & 0.07 & 5.55 & 0.00 & 0.26 &
0.55 \\
23 & visual & \~{}\~{} & speed & 0.26 & 0.06 & 4.66 & 0.00 & 0.15 &
0.37 \\
24 & textual & \~{}\~{} & speed & 0.17 & 0.05 & 3.52 & 0.00 & 0.08 &
0.27 \\
\hline
\end{tabular}
\end{center}
\end{table}
Yves.