I've been working on my own list over at everythingicafe.com, if you guys want to help us out there.
Check it out. Our list is looking a little more complete, here's what we have so far at the time of me writing this post (some of it ripped off from this thread as well

):
New Features in 3.0:
- Cut/Paste
- Copy/Paste
- MMS
- Landscape keyboard in Notes
- Landscape keyboard in Mail
- Landscape keyboard in Messages
- Forward texts or picture messages
- Delete individual texts or picture messages
- Tethering
- Stereo bluetooth
- Spotlight search
- Search in Notes
- Search in Mail
- Search in iPod
- In-App purchases
- Option to have double clicking the home button go to the Spotlight Search
- Option to have double clicking the home button go to the Camera
- Preview icon in lower left hand corner for last shot taken in Camera app
- Shake to shuffle in iPod
- Scrolling of screenshots in App Store
- Type of phone used under each call in Recents (i.e., mobile, home, work, etc.)
- Call history for each contact
- Option to Share Contact in each contact listing
- Hold link in Safari to Copy
- Hold link in Safari to Open in New Page
- Auto Fill contact information, usernames and passwords in Safari
- Login to your YouTube account
- See Comments in YouTube
- Subscribe in YouTube
- Rate in YouTube
- Shake to undo what you have typed
- Option to retry sending failed text messages, indicated by red exclamation point next to text
- Turn-by-turn GPS capabilities
- Maps can be run inside other applications
- Access to dock port for accessories to communicate
- Peer-to-peer connectivity using Bluetooth (no Wi-Fi required)
- New Voice memo application
- Extended Parental controls
- Anti-phishing
- Wi-Fi auto login
- Note syncing in iTunes
- Improved Stocks app
- New calendar types (CalDAV)
- Prompt to confirm deleting a note
- Prompt to confirm deleting a photo
- Option to select multiple photos to attach to an email
- "Find My iPhone" option for MobileMe users
- Unlimited size podcast downloads over 3G
- Pushing home button on first home screen takes user to Spotlight
- Pushing home button on Spotlight takes user to first home screen
- Variable speed playback for audio books
- App Store subscriptions
- Push notifications
- Audio/Video tags
- Live streaming
- Calendar subscriptions
- iTunes login
- iTunes account creation
- Encypted profiles
- LDAP (directory services)
- VPN on-demand
- EAP SIM
- Proxy support
- OTA profiles
- Revoke certificates
- Exchange ActiveSync Policies
- Media scrubber
- More languages
- Improved keyboards
- Failed app updates now are shown in a duplicate icon and labeled "Paused"
- When selecting multiple email to forward/delete, any unread emails' blue dot are shown next to the red selector dot instead of being overridden by the red selector dot.
- Non-contact phone calls list their city and state of origin in Recents and Visual Voicemail under the number.
- Ability to change ringtones straight from Favorites
- Lap time display in Stopwatch
- Polished Phone, Messages, and iPod icons
- Semi-transparent menu bar in Safari landscape mode