As expected, Facebook has removed the Discussions tab and the Reviews tab from all Pages. Both were supposed to be removed on October 31, 2011, but were instead officially killed this week, starting on November 15, 2011.
The only point of reference left is the Facebook Help Center question "What happened to the Reviews and Discussions tabs on my Facebook Page?" The answer has been updated recently:
We've found that the best way to encourage conversation and feedback is through posts and comments on your Wall, so we're removing the Reviews and Discussions tabs for now. We're working on tools to help you moderate, filter and manage content in one powerful place. Stay tuned.
You won't be able to access your reviews and discussions once they're removed, so please save this content if you'd like to keep it for future reference.
On place pages with a location, fans can still write a recommendation for their friends or others from the right-column that says Recommendations.
The last paragraph, which links to the Recommending places, wasn't there before. If you were using the Reviews app, this is your only option now.
If you were using the Discussion app, also known as Discussion Boards, to host a basic forum, Facebook would apparently prefer that you just use the Wall. Alternatively, there's a third-party app called Forum for pages you may want to check out.
Facebook hasn't given a reason for killing these two apps, but I'm sticking to my theory. Both the Discussions tab and the Reviews tab are not picked up by the newly launched Ticker and the upcoming Timeline and Open Graph rollout. Walls on Pages are, however, and so Facebook has decided to just kill these apps rather than updating them to make them work with other updates to the service.