One of the most welcomed improvements is that apps will finally be installable on microSD cards. This is something the Android community has been wanting for a very long time, as the internal memory capacity is minuscule compared to the 8GB, 16GB, and 32GB available on microSD cards.
Froyo will also bring an "update all" function in Android Market that allows multiple apps to be updated simultaneously. This alone makes me anxious to get Android 2.2 on the EVO, as I've been spoiled by the feature on my iPhone for years and have previously moaned about its absence when I had my Nexus One. Even better than "update all," however, will be the option for apps to update themselves automatically. Nice!
The new Backup Manager in the settings menu will let us backup and restore user data in apps so that information isn't lost when moving to another device, reinstalling apps, and doing factory resets. There will also be Android Cloud to Device Messaging with two-way push sync and bug reporting that lets users submit crash/freeze reports to app developers.
In other words, the HTC EVO will be even better!