Research In Motion (NYSE:BB) just can't catch a break. Then again, luck finds doers -- and RIM hasn't done much to deserve a break lately.

The latest nail in the BlackBerry platform's coffin comes straight from the Pentagon, where RIM's smartphones have long been the only approved communications gadget. Top-secret information deserves top-notch security, and only RIM's product would do. It was a big deal when a handful of BlackBerry 7 devices were approved for Defense Department use last spring, for example.

If corporate IT bosses were RIM's best friends, the military was its soul mate.

But that just changed in a hurry.

The Defense Department just commissioned a new system to support Android and Apple (NASDAQ:AAPL) devices on military networks. The new solution must support "at least 162,500" non-BlackBerry smartphones and tablets, and could be expanded to reach 8 million devices in the end. If the network can manage and connect BlackBerry devices, too, that's a bonus -- but it's not an absolute requirement.

Losing the Pentagon's absolute trust means losing a major selling point -- perhaps the last one RIM had left. The company can no longer claim to blow the competition's security features away with a quick nod toward the banks of the Potomac.

The BlackBerry 10 platform upgrade is RIM's last hope. But that solution keeps getting postponed, allowing Apple and Google (NASDAQ:GOOGL) to steal more mindshare every day. Maybe even the recently launched Microsoft (NASDAQ:MSFT) Windows 8 software has time to gain a foothold before RIM takes another swing.

And by then, it'll be far too late to make a difference.