Quick Google search reveals lots of ways but I prefer the multicols environment in the multicol package:


\begin{frame}
\begin{multicols}{2}
First column of stuff \newpage
Second column of stuff
\end{multicols}
\end{frame}


The {2} in the opening of the multicols environment gives the number of columns.

If you want to use block environments (as I often do) with multiple columns, the blocks will run into adjacent columns unless you do something about it.