iPhone 3.0 New feature
When iPhone was launch it was very disappointed that they do not support bluetooth. Finally in their this latest firmware they have included bluetooth support which will allow application communication over bluetooth or through the dock connector using standard or custom protocols.
10:20AM – Apps talk to accessories via the dock connector and via Bluetooth. Supports standard protocols (playing music, album artwork, etc.) and you can build custom protocols.
“With iPhone 3.0 we’re going to take this to the next level: we’re going to enable devs to build custom accessories that talk right to the iPhone.” This is exactly what people have been wanting. “You can give the iPhone an equalizer to a speaker system. Here’s another example: FM transmitter, which would find the optimal broadcast channel and play your music. Here’s another class we think will be interesting: medical devices.”
There are a lot of new feature in iphone 3.0 but i cover only some interesting feature. For full coverage you check it out at gizmodo.
Copy and paste text – When you double-tap over text, you will get a “cut, copy, and paste” bubble dialog. Double-tap again and a “paste” bubble will appear if there’s anything stored in your clipboard.
New Spotlight - iPhone OS will allow you to search across the entire information contained in your device, no matter where, as soon as the information is supported it. If an application is written to support the new Spotlight, its data will also be available in the search.

iPhone 3.0 spotlight
Landscape keyboard - Apple has added the landscape keyboard mode to other applications, like Mail, SMS, and Notes.

iPhone 3.0 landscape keyboard
Multimedia messaging - A big one to send rich content to people without mail-enabled telephones: The new MMS function will allow you to include everything, from images to sound to vcards (no word on video, however.) Personally, I find these usesless having email, but some people seem to want it.
Turn-by-turn directions - Developers will also be able to create turn-by-turn applications using the GPS information from the iPhone and combining it with their own maps, without depending on 3G connectivity or Google.

iPhone 3.0 turn by turn
Push notification finally coming - Hopefully this time it will be true. Push notification means that your iPhone OS 3.0 applications will finally be able to receive messages from the intarwebs automagically, so you can have an Instant Message application and have your iPhone vibrate or make a sound when a new message comes in, even if the application is not running.

iPhone 3.0 push notification
Source: gizmodo
It is really a good news for iphone fans