Most data center managers would agree that when you have water dripping through the ceiling of your data center, you already have a huge problem. A company called Turtle Shell Industries is marketing a product to provide the last line of defense in this worrisome scenario.
The product consists of a lightweight polycarbonate shell placed over racks and cabinets to protect it from overhead leaks and debris, and comes with pull-down curtains that can be extended for additional protection for IT equipment. A motorized curtain is available for facilities that are monitored remotely, so they can be deployed without staff on site. The Turtle Shell FAQ says the unit can be customized, but doesn't specifically address how fire suppression might be handled.
Many data center operators seek to manage risk of water damage by limiting the number of penetrations in roof membranes, or perhaps by seeking a dry climate during site selection. Most of the instances of water-related disruptions have been from floods rather than ceiling leaks. Examples include the 2007 outage at a T-Mobile data center near Seattle, the flooding in Istanbul last fall and the water main break in Dallas earlier this year. Here's a video providing an overview of the product. This runs about 4 minutes, 30 seconds.