Well, nothing cloud related or sync related, so that's probably farther out then I hoped.

Major points seem to be:
1. Multitasking - Pretty much what was predicted, APIs provided so apps can run background related tasks, instead of having the full app in the background. Pandora can still play music and take over the system media controls, and GPS apps can keep routing users. Switching between apps is a double tap on the home button, and it reveals running apps in a tray that appears at the bottom. Looks very similar to the add a widget to the dashboard interface on OS X. I'm assuming this solves the issue of not being able to hold an SSH session open while referencing a web page, but not 100% certain.

2. Folders for organizing apps. The unique twist here is how it's done. Drag an app onto another one, and it makes a folder, defaulting the name to the category the two apps are in. This bumps the visible app limit from 180 to 2,160.

3. Mail. Unified inbox, fast inbox switching if you still want them separate, multiple Exchange account support (so now people can have gMail via Exchange along with work mail), threaded messages, and much like the iPad, ability to open attachments with third party apps. Unfortunately, still no smart folder support.

4. iBooks. Looks like 4.0 will build it into the OS, and sync page read/bookmarks across devices like the Kindle Whispersync.

5. Enterprise features including better encryption of mail, encryption for app data, and wireless app distribution.

6. Game Center - Think XBox Live, Steam, or Playstation Network. Friends lists, achievements, matchmaking and leaderboards. A few independent parties were doing similar, but very few games used the platforms out there. Apple officially supporting it should mean a lot more games will tie into it.

7. iAd, an advertising platform. This is probably the counter shot for Google entering the phone market. HTML5 based ads, allowing full video, mini games, and so on.

Multitasking is limited to the iPhone 3GS, the newest iPod Touch, and the iPad. The rest of 4.0 will still come out for the 3G and second gen iPod Touch, but no word about the initial iPhone. Looks like this is where the Apple mobile platform fractures a little bit, dumping off the 3 year old devices. Being that people tend to update their phones quicker then every 3 years, shouldn't be too big of a deal there. Will be interesting to see if this pushes people to upgrade their iPods more often though.

I'll be downloading the SDK and beta firmware here shortly, but it looks like it's covered under the standard prerelease NDA, so I won't be able to comment on it.