Apple announced the developer release of iPhone OS 4.0 with 7 major features and over a 100 other updates.
The biggest news is that the iPhone finally has multi-tasking ! So for the nay-sayers here is proof that Apple does care about the user.

The 7 major 'tentpole' features are:

• 1. Multi-tasking
• 2. Folders - organize apps into folders
• 3. Unified Mail Inbox
• 4. iBooks
• 5. Advanced Enterprise Support
• 6. Live Network Gaming
• 7. Mobile Advertising

Dozens of other features:
Other minor features highlighted in a slide of iPhone 4.0 enhancements include:

• File & delete
• Mail search results
• Search SMS/MMS messages
• Web search suggestions
• Choose image size in Mail messages
• Bluetooth keyboards
• CalDav invitations
• Larger fonts for Mail, SMS & alerts
• Cell data only setting
• Spell check
• Persistent Wi-Fi
• Gift Apps
• Birthday calendar
• Recent Web searches
• Create Playlists
• Top Hit in search5x digital zoom
• Nested Playlists
• CardDav
• Tap to focus videoUpload workouts to Nike+Places in Photos
• iPod OutHome screen wallpaper
• Search SMS/MMS messages
• Wake on wireless