According to 9to5, the new product will include a Dynamic DNS system to tie in with MobileMe; this will provide username.me.com domains for easier access across the Internet. In addition, the device will include AFP filesharing and Time Machine backup stores. The device will not run off of Mac OS X Server, as you might suspect; rather, it would run the same system and processor that the Time Capsule does.
You can read more about this rumor, and read more details about the rumor on the 9to5 Mac website. Do you think Apple is about to jump further into the NAS market with a supercharged Time Capsule?