Just a few days after the launch of Amazon's new Kindle 2.0, an upgrade to version 2.0.1 began slowly rolling out. Judging from posts on the Kindle 2 forums, a few Kindles have been upgraded as of today (3/2), but most have not.
It seems unusual to push out an upgrade so soon after a product launch, and Amazon so far hasn't said a thing about it. There's no information on the Kindle support pages about this upgrade at all.
How do you know if you've received the upgrade? From the HOME page, press the MENU button. Select "Settings" from the menu. Your version number will appear at the bottom of the screen. If you press MENU again from the Settings page, you will see an "Update Your Kindle" menu item. If this item is grayed out, it means the update has not yet been pushed to your Kindle.