Add horizontal separator between (landscape) slides

Using beamer, I have a created a series of slides. Can I print 2 slides per page (as done in the pdfpages package) but add a horizontal line (not an entire frame) to separate the pages vertically:

I.e., I would like

slide 1

------- <-- this line is what I want

slide 2

This is how it's done (for file beamer.pdf). How much do you want automated?

\documentclass{article}
\usepackage[margin=1in]{geometry}
\usepackage{graphicx}

\begin{document}
\begin{center}
\includegraphics[height=0.45\textheight,page=1]{beamer}
\vfill\rule{\textwidth}{1pt}\vfill
\includegraphics[height=0.45\textheight,page=2]{beamer}
\end{center}
\end{document}


pdfpages has a picturecommand option, but I didn't know how to use it in this case. But as it already loads eso-pic, it's easy to draw a line on background with it.

Note: I'm not used to picture, so if the code can be improved, please do it.

\documentclass[a4paper]{article}
\usepackage{pdfpages}