Apple Inc. Chairman and CEO Steve Jobs speaks during an event at Apple Inc. in Cupertino, Calif., Thursday, April 8, 2010.Eric Risberg/The Associated Press
Multitasking
Not only can you have multiple apps running, but you can move slow-loading apps into the background and continue working on others with no lag, as well as auto-activated push notifications and location updates.
Folders
As simple as it is great: instead of page after page of apps you can store a bunch of them in one folder, which can also live in and launch from the dock. The maximum app spots in the old system was 180, with OS 4 you can potentially have 2,000 apps on your phone.
Enhanced e-mail
A much needed update to the inbox: Add multiple Exchange accounts, and fast inbox switching. E-mail will also be sortable by thread.
iBooks
This new app for the iPad will be ported to OS 4, Jobs announced more than 600,000 titles have been downloaded for the Apple reader already. That number is bound to shoot up when users can sync their iBook accounts on iPad, Touch or iPhone.
Enterprise
For business users, IT departments can remotely manage the device, install VPN clients and wirelessly update new apps to user phones. Also enhanced encryption.
Game centre
There are more than 50,000 iPhone games. Apple is going to create a social gaming network that matchs you with other people with similar skill levels. Plus leaderboards and achievement settings.
iAd
Mobile advertising inside apps has been sporadically applied, and usually not well. The iAd standard will keep the ads inside the apps, they will all be hosted and served by Apple, and 60% of the revenues will go to the developer.
How big is that? Jobs says: "The average user spends over 30 minutes using apps on their phone. If we said we wanted to put an ad up every 3 minutes, that'd be 10 ads per device per day - about the same as a TV show. We're going to soon have 100 million devices. That's a billion ad opportunities per day!"