This appears to be the current record - <i>16</i> languages:
<a href="https://github.com/mauke/poly.poly/blob/master/poly.poly" rel="nofollow">https://github.com/mauke/poly.poly/blob/master/poly.poly</a>
Love writing those! So much effort. Here is a sh/bat polyglot I did a while back <a href="https://gist.github.com/alganet/9531262" rel="nofollow">https://gist.github.com/alganet/9531262</a>
Once saw a polyglot program used as both a build script and the program to build. It was part C++ and part batch script, though for the most part the C++ part just #included several cpp files.