columns/alignment with itemize

You can't do this particular mixture of itemize and tabular out of the box. But the listliketab package can help. The purpose of that package is to make tables looks like lists.

\documentclass{beamer}
\usepackage{listliketab}
\begin{document}

\begin{frame}
    \frametitle{Title}
    \begin{listliketab} 
    \storestyleof{itemize} 
        \begin{tabular}{Lll}
            \textbullet & Topic Apple: &Something to say about it \\
            \textbullet & Topic Watermelons: &Something different
        \end{tabular} 
    \end{listliketab}
\end{frame}
\end{document}

Works in beamer and other all other classes (that I know of).

How about this:

\documentclass{beamer}

\begin{document}

\begin{frame}
    \frametitle{Title}
    \begin{tabular}{@{\textbullet}ll}
        Topic Apple: &Something to say about it \\
        Topic Watermelons: &Something different
    \end{tabular}
\end{frame}

\end{document}

Which results in

You can also change the \textbullet by, for example adding another column which will hold the item marker (which you can then control using beamer).

Since other suggestions here didn't work for my two-column document style, here is my plain-TeX hack to achieve something similar:

\begin{itemize}
\setlength{\itemsep}{0cm}%
\setlength{\parskip}{0cm}%
\item{\ \hbox to 3cm{Topic Apple: \hfill}\texttt{Something} to say about it}
\item{\ \hbox to 3cm{Topic Watermelons: \hfill}\texttt{Something} different}
\end{itemize}

Here is a brief explanation (before I forget it :) ):

• the \itemsep and \parskip solve a different problem in my document (I include them since I'm not sure if they have an effect on the rest or not)
• The first space '\' in the \item, is to cheat the \itemize environment - so it thinks it starts with plain text (otherwise, Latex will typeset everything in the first \hbox above the bullet point)
• The '\hbox to 3cm{}' creates a box 3cm wide, in which the contents will be typeset - however, by default, the text contents (i.e., the 'glues') in this \hbox will be stretched across the entire width of the \hbox
• To solve this stretching problem, we enter a '\hfill' at the end of the \hbox: thus, the text in the \hbox is typeset first, and then the \hfill inserts a space stretching to the end of the 3cm width - which effectively shows the text as 'raggedright' (i.e., left aligned)
• (I had a '\texttt{}' word where I wanted the alignment indent to happen in my own case, so I included it here too)

Of course, to have this code usable, one should use a length variable before it:

\newlength{\tmplen}
\setlength{\tmplen}{3cm}

and then use \tmplen in the \items instead, as in:

...
\item{\ \hbox to \tmplen{Topic Apple: \hfill}\texttt{Something} to say about it}
...

... since you'll have to manually set the box width with this approach.

Well, hope this helps someone,

Cheers!