The firmware is updated from version 1.0 to 1.1, which is released on Mar 27, 2008.
It's reported that the new firmware contributes to lens compatibility with recently announced E-420. And, surprisingly, I found this update greatly enhanced and optimized the AF function when working with my E-510.
It's highly recommended for all lens users to update the new firmware. The update can be downloaded and installed via the Olympus Master software.