Research In Motion has filed suit against Handspring alleging that the company's Treo organizers infringe on a RIM patent. Apparently RIM feels the keyboards on some of the Treo devices infringe on a patent that they hold. Specifically the keyboards on the Treo k180, Treo 270 and Treo 300 models.
The Handspring Treo features a small keyboard that can be typed on using one's thumbs, as does RIM's BlackBerry device.
RIM has filed similar law suits in the past against competitors. In July they filed a suit against rival Good Technology accusing them of unfair competition, false advertising, trademark infringement and trademark dilution resulting in the unlawful use of the RIM and BlackBerry marks.