Top hit in Search: probably something skin to the result you get in Spotlight, the most common activity resulting from a search would get automatically put to the top of the list next time you search for it. Like for example, all I need to do is type "h" into Spotlight and Handbrake is right at the top.
iPod out: Dunno, hopefully something akin to a controllable interface for the iPod when plugged into a TV. Something like a portable
TV.
Persistent WiFi: Currently, the iPhone and the iPod touch do not maintain a constant WiFi connection when asleep. This means that the iPhone is using cellular data to check mail and get push notifications when it's asleep and the iPod touch needs to turn on it's connection (though you don't see it) at random times. Persistent WiFi means it's connected to WiFi all the time.
Wake on Wireless: This one I don't get. It's a feature of some very recent Macs that mean they can be asleep but when you need to access them wirelessly they wake up. Previously one would have to physically go and wake the machine up. Why it's required for the iPhone I don't know.
Recent We Searches: Look at the search bar in OS X Safari, your recent web searches are listed in the drop down menu - same thing coming for the iPhone.
Upload workouts to Nike+: You won't need to sync with iTunes to upload your workouts, the phone can do it over the air.
File & Delete Mail Search results: Dunno, maybe like a "saved search" thing, smart-album maybe?
Wireless App Distribution: Enterprise feature allowing companies to push out custom in-house apps to all the employee's phones over-the-air so they don't need to sync with iTunes.
Mobile Device Management: Another enterprise-level feature.
Remember, the current 4.0 release is Beta software. Many user-level features are missing as it's for developers only. There will be many of these releases leading up to the official release.
