Nokia surely believes in the maxim, ‘when it rains, it pours’. Following on from the N97 and the N96, the E51 has also been given a new firmware in the form of v400.34.011. According to the release notes, this software release brings improvements and increased stability in Mail for Exchange and SMS reception. It also improves stability and usability for VoIP and WLAN. The release also mentiones ‘robustness improvements when pressing the Home key’, translating to better responsiveness perhaps.
Thus, the update brings more of bug fixes than anything else, flash is the the same old at 2.1. If you are concerned, the update also makes the device ‘unhackable’ for now. Since the E51 does not support over the air downloads or user data preservation, you will have to use the NSU to update and will loose all data on the phone memory.