The "geniuses" at Google recently updated the Gmail app for Android to version 2.3.5, and it is available now on the Android Market. Amazingly, this newest version of the Gmail sync app actually claims to be able to improve your battery life, amongst several other performance enhancements and tweaks. One of its newest features allows you to only sync your priority emails, which will allow your phone to use less bandwidth and less power from the battery. Also, the new update includes a slew of additional new features like the ability to set “Show Pictures” for specific senders and a new option that allows you to set custom alert tones for the various labels. Furthermore, you can also now turn off sticky message actions, and the app also has better TalkBalk support for accessibility.
Here's a link below to the market for you to look at it. [Update: Apparently, there is word that this new update also blocks 3rd party tools from accessing your Gmail, which could be a real pain for many users. This has not been confirmed at this time, but you can read this blog-post about it and decide for yourself before you try it: Android Gmail App Blocks 3rd Party Tools
Source: PhoneArena and The Android Market