Cisco Systems sued Apple in federal court Wednesday, saying the computer maker’s new iPhone violates its trademark. The lawsuit, filed in U.S. District Court for the Northern District of California, came just a day after Apple CEO Steve Jobs unveiled the Apple iPhone in dramatic fashion at a trade show in San Francisco. But even while Jobs was trumpeting the product during his keynote address to Apple faithful, the matter of the product’s naming had not been resolved behind the scenes between two of the biggest names in Silicon Valley.