The Goat Simulator Facebook page reveals plans for a patch coming in May bringing split-screen multiplayer and other enhancements to the game (thanks PC Gamer). Here's word:

A lot of you have been asking for DLCs for Goat Simulator. However, we wanted to do a free update instead, because goats don't like to charge for new content.

Patch 1.1 for Goat Simulator will be adding a whole new playable map, roughly the size of the original map, local splitscreen multiplayer, new achievements, new goats, and more!

Patch will come in the middle of May!