Take your API key and add it to your wp-config.php like this:
//SITEWIDE AKESMIT KEY define('WPCOM_API_KEY' , 'API_KEY_HERE');
This will hide the key from any site on your network that activates Akismet and will use your key automatically!
I discovered this today, so I thought I just had to share.
The plugin still doesn't activate automatically. Does anyone know a quick and simple way to do this?
It won't work in the mu-folder (I tried lol)