You can find all the Secret Tester posts in the new Testers category. 
There’s only one live one at the moment (it’s marked with a 
).
The Review Guide has had a makeover too, and there are a couple of tips in there on how to set notifications up so you never miss a new one.
And there’s a new Tester List Update topic too, which you can set to Watching (which means you’ll get a notification every time it’s updated )