During its fourth-quarter earnings call today, RIM revealed that its upcoming BlackBerry Playbook tablet would be compatible with applications developed for Google's Android operating system.

Android app compatibility will come via a pair of app players, which RIM says will be available via the RIM App World.

Using a special API, developers would easily be able to port existing Android apps to the Playbook tablet, RIM said.

The announcement comes with a catch, however. RIM says that the Android compatibility won't be available at the Playbook's April 19th launch. Instead, RIM plans to show off the features at its May BlackBerry World event taking place in Orlando, Fla.

The news comes shortly after RIM's shares dropped 10% in after-hours trading.