Latex learning, Learning Latex

This is some notes of my experience in using Latex. Most of the case, you can find the answer using Google.
However, I have got a problem, I can't solve it. I would like to make a table like belows, but cannot merge cell without loosing the arrangement:

Here is the code:


\begin{table}[ht]
  \centering
  \setlength{\tabcolsep}{1pt}
  \begin{tabular}{|p{1.8cm}|l|l|l|l|l|l|l|l|p{4.8cm}|p{4.5cm}|}
  \hline
                 & \multicolumn{7}{|c|}{\textbf{Supported Devices}}     & & & \\ \hline
   \textbf{Site} & \begin{sideways}Mobile Site\end{sideways}   &
                   \begin{sideways}Android\end{sideways}       &
                   \begin{sideways}iPhone\end{sideways}        &
                   \begin{sideways}Blackbery\end{sideways}     &
                   \begin{sideways}Windows Mobile \end{sideways} &
                   \begin{sideways}Symbian\end{sideways}       &
                   \begin{sideways}Palm\end{sideways}          &
                   \begin{sideways}W3C Geo API\end{sideways}   & \textbf{Significant features} &
                                                                 \textbf{Notes}\\ \hline


    \textbf{FourSquare}   & x & x & x & x & x & x &   &   & Support games for differentiation &    \\ \hline
    \textbf{Facebook}     & x & x &   &   &   &   &   & x & High number of users & Not supported in Vietnam \\ \hline
    \textbf{Latitude}     & x & x & x & x &   &   & x & x &  &    \\ \hline
    \textbf{Gowalla}      & x & x & x & x & x &   &   & x &  &    \\ \hline
    \textbf{Twitter}      & x & x & x & x & x &   &   & x &  &    \\ \hline
    \textbf{Yelp}         & x & x & x & x & x &   & x &   & Focus on information searching &    \\ \hline
    \textbf{Loopt}        &   & x & x & x & x &   &   &   &  &    \\ \hline
    \textbf{GyPSii}       &   & x & x & x & x & x &   &   &  &    \\ \hline
    \textbf{IYOUIT}       & x & x & x & x & x & x & x & x &  &    \\ \hline
    \textbf{Yoo! }        &   &   &   &   &   &   &   &   & First social network supported location awareness in Vietnam & Not have mobile web version   \\ \hline
    \end{tabular}
  \caption{social networks support location aware}\label{table1}
\end{table}