Apple released iPhone update 2.0.1, the first update to the iPhone 2.0 software update.
The iPhone Software update is available through iTunes and fixes bugs according to Apple's release note.
The first users who have installed the new iPhone update encountered also improvements in speed and usability.

According to AppleInsider you can now drag an app icon across multiple pages in one motion, backups run faster and several apps load faster and are more responsive.
So looks like it is worth it to sit through a full backup and then download 250MB of the update and have it installed.
If you want to play it ultra safe, wait until this evening to see if anybody reports any issues with the iPhone Update 2.0.1. Update: If you have jailbroken your iPhone 2.0, you should wait with the update, because PwnageTool 2.0.1 is not working on iPhone Software Update 2.0.1.

Apple already seeded a beta of iPhone 2.1 Software Update to developers.