The enhancements include: more Airplay ability, Safari performance, iTunes Home Sharing, iPad Side Switch option, and Personal Hotspot for iPhone 4.
Airplay is wireless technology that allows you to stream content from your iPhone, iPad or iPod touch to your HDTV via Apple TV. That means music, movies and photos are available to be “broadcast” to other supported devices.
Safari Performance is improved so loading pages is faster. (Apple’s claim).
iTunes Home Sharing allows you to play your entire iTunes library from anywhere in the house over a shared Wi-Fi network. This works with movies, TV shows, music, audiobooks, etc. With this technology, you do not need to redownload or sync.
The more specific updates are as follows:
– Share iPhone 4 cellular data with up to 5 devices (combination of up to 3 Wi-Fi, 3 Bluetooth, and 1 USB)
iTunes Home Sharing
– Play music, movies, and TV shows from a shared iTunes library on a Mac or PC (requires iTunes 10.2)
New AirPlay features
– Play videos from the Photos app including the Camera Roll album, iTunes previews, enabled third-party apps and websites on Apple TV
– Play slideshows from Photos on Apple TV using transitions available on Apple TV
HD video out using the Apple Digital AV Adapter
– View 720p HD videos from Videos app, iPod app, Photos, YouTube, Safari, Keynote, and enabled third-party apps on an HDMI display
– Push notifications for comments and follow requests
– Post and Like songs directly from the Now Playing screen
– Parental controls
– Messages setting for number of times to repeat an alert
– iPad side switch setting to lock screen rotation or mute audio notifications and sound effects
Single tap conference call dialing with a pause to send a passcode
You can read about the new and improved features here.