Research In Motion (RIM) has filed a complaint in the United States District Court for the District of Delaware against Handspring, Inc..

The complaint alleges that certain devices in the Treo Communicator series (Treo k180, Treo 270 and Treo 300) manufactured, marketed and sold by Handspring infringe the claims of a patent associated with keyboard features implemented in RIM's BlackBerry handhelds.

This complaint could cause serious damage to Handspring should RIM prevail, as the company is banking its future on devices such as the Treo Communicator series that are built around Blackberry-like thumb-based keyboards. Further details of the complaint were not disclosed.