Apple has announced that OS 4 for the iPhone will have multitasking. This is a break for the iPhone where many users complain that they want to run multiple applications. Apple has released the API’s to developers that allow for this functionality so you can expect there to apps that will have this functionality soon. To get a list of the programs running the user would simply have to press the home screen button twice to view this information. The trade off with the use of multitasking is that you can expect your battery life to be less than it is now. The other downside to this is that only users with the iPhone 3GS and up will benefit as this is will not be supported by the iPhone 3G and older.
Another new feature to the iPhone OS is that it will support the ability to encrypt all e-mail and attachments, unlocking them with a user-entered pin code. This means that if the phone is stole sensitive emails will not be at risk of exposure. It will also support Exchange 2010 and allow users to sync multiple exchange accounts to a single device. A platform that will let advertisers and software developers embed a range of multimedia ads directly into an iPhone 4 application.
The iPhone is stilling missing flash and java support and will not likely support it in future releases.
Tech Blog 