\documentclass[svgnames]{beamer}
\setbeamertemplate{background canvas}[vertical shading]%
  [top=blue!1,bottom=blue!30]
\setbeamertemplate{navigation symbols}{}
\usepackage{tikz}
\usetikzlibrary{matrix}
\newcommand*\up{\textcolor{YellowGreen}{$\blacktriangle$}}
\newcommand*\down{\textcolor{Red}{$\blacktriangledown$}}
\newcommand*\const{\textcolor{darkgray}{\textbf{--}}}
\newcommand*\head[1]{\textbf{#1}}
\newenvironment{matrixtable}[4]{%
  \begin{tikzpicture}[matrix of nodes/.style={
    execute at begin cell=\node\bgroup\strut,
    execute at end cell=\egroup;}]
  \matrix (m) [matrix of nodes,top color=blue!20,
    bottom color=blue!80,draw=white,
    nodes={draw,top color=blue!10,bottom color=blue!35,
    draw,inner sep=2pt,minimum height=3.1ex},
    column sep=1ex,row sep=0.6ex,inner sep=2ex,
    rounded corners,column 1/.style={minimum width=#1},
    column 2/.style={minimum width=#2},
    column 3/.style={minimum width=#3},
    column 4/.style={minimum width=#4}]}%
{;\end{tikzpicture}}
\begin{document}
\begin{frame}[fragile,bg=lightgray]
\begin{center}
\begin{matrixtable}{1.2cm}{2.4cm}{1.2cm}{0.6cm}{
  \head{Rank}   & \head{Distribution} & \head{Hits} & \\
  1 & Ubuntu    & 2114 & \down  \\
  2 & Fedora    & 1451 & \up    \\
  3 & Mint      & 1297 & \const \\
  4 & OpenSUSE  & 1228 & \up    \\
  5 & Debian    & 910  & \down  \\
  6 & Mandriva  & 907  & \up    \\
  7 & PCLinuxOS & 764  & \up    \\
  8 & Puppy     & 738  & \up    \\
  9 & Sabayon   & 671  & \up    \\
 10 & Arch      & 625  & \down  \\
}
\end{matrixtable}
\end{center}
\end{frame}
\end{document}