The prompt "File: Supercow.zip ... — come up with a post" likely refers to a few different things, depending on whether you're talking about a game, a development project, or a technical issue. Here are the most likely interpretations:

Could you clarify if you are looking for a for the game, a technical announcement for a developer project, or help with a programming "POST" request ? I have ported at90can128 to arduino - Exhibition

There is a well-known user or project named "SuperCow" in the Arduino community related to porting AT90CAN128 to Arduino; you might need a post announcing a code update or a bug fix for a .zip library.

You might be looking for a social media or forum post about the 2007 platformer game SuperCow (sometimes called a "Post-Soviet Masterpiece").