SharePoint Hut

So I found two sites and combined them to get what I needed:

http://microsoftepmsolution.blogspot.com/2011/10/epmsharepoint-2010-how-to-display-farm.html

This is how to get the version of the farm via powershell:
Get-SPFarm | Select -ExpandProperty BuildVersion

This is how you find out the corresponding CU/ Service Pack for the build version:

http://www.toddklindt.com/blog/Lists/Posts/Post.aspx?ID=224

Thanks to Todd on this one.