I believe Autodesk Fusion 360 automatically updates at each launch, but if you want to verify that you have the latest Shopbot Post Processor you can check out this link:

http://cam.autodesk.com/posts/

You'll need to search on Shopbot in the vendor field to find it.

I like it because it gives details about what has changed in the Shopbot.cps post process that creates the G-Code.sbp file.

1/15/2016 Fixed missing formatting for generic Shopbot post.
12/18/2015 Fixed generic ShopBot post.
8/27/2015 Added more decimals for feed output for the generic Shopbot OpenSBP post.
8/26/2015 Major update of the generic Shopbot post. Added new properties to select 5-axis and 4-axis machines.
10/19/2014 Updated multi-axis support for generic ShopBot OpenSBP post.
1/21/2014 Updated generic Shopbot post.

For now I'm believing the Shopbot ISO.cps is just the original post process branch and is no longer actively used. Feel free to correct me as I'm muddling my way through this.