UPDATE: MacRumors also found remote file access for MobileMe users:

Access files on a networked drive from anywhere - Allows MobileMe subscribers to register their AirPort Express Base Station or Time Capsule with their MobileMe account, providing them access to their files from anywhere via the Internet. Drives will appear in the Finder sidebar like any other attached drive, acting just like a personal file server with remote access.

ORIGINAL: It was rumor, it is now fact. Apple has released new versions of their Airport Extreme (WiFi router) and Time Capsule (WiFi router + HD) base stations, with simultaneous dual-band Wi-Fi:

For maximum range and compatibility, AirPort Extreme works simultaneously on both the 2.4GHz and 5GHz bands, allowing all the devices on the network to use the most efficient band automatically. And AirPort Extreme uses the latest 802.11n wireless technology so you can enjoy up to five times the performance and up to twice the range of 802.11g wireless networks.

Think of it as having 2 lanes on your WiFi highway. While your 802.11g iPhone is out taking a Sunday drive on your network, it's no longer blocking traffic in front of your screaming fast 802.11n MacBook.

The only other new feature we could find was Guest Accounts:

Now you can set up a separate Wi-Fi network with a separate password for your visitors. Simply enable the new guest networking feature, and your guests can use the Internet but can't access other parts of your private network, such as your computers, printers, and attached hard drives.

Anyone going to upgrade? Anyone in the market for a new router going to consider one of these?