There have been legends from the Greeks and the Indian cultures of metallic warriors, but nothing as concrete as what came to fashion the beginnings of mecha. In 1880, the legendary Jules Verne wrote, what now would be concerted streampunk, a book called The Stream House. This book featured a controllable stream-powered robotic elephant. It is more likely the much better known 1898 War of the Worlds by H.G. Wells and its Martian tripod piloted war-machines forged the the beginning of mecha in the popular culture, certainly leading to the metal-machine-aliens popular in the 50's and 60's.
There is hope for finally seeing a true giant robot mecha on the silver screen, Guillermo del Toro's upcoming Pacific Rim will feature massive mecha called Jaegers. It seems from what little information there is, these Jaegers were created to fight giant monsters, similar to the ones from Japanese films. I had hoped this would be a very film, but after seeing the scale of the mech, and the basic plot, I'm officially disappointed. Why are there few mainstream films that contain giant robots and trend more towards the armored power suit? My guess would be usability for the filmmaker to show the mech within the environment of the film and APS seem more believable to an audience. 60 foot robotic suits would have difficult to swallow in Avatar. So, I guess I will wait on the Battletech film awhile longer...sigh...
Where the hell is my Mecha-Fighting Simulator?!