Microsoft Exchange ActiveSync support
Support for Apple's new MobileMe service
Push email
Push contacts
Push calendar
Global Address List
Certificates and Identities
WPA2/802.1x
Enforced security policies
Extra keyboard languages including Chinese and Korean
Cisco IPsec VPN support
Device configuration
Remote wipe
Ability to view PowerPoint attachments
Ability to view iWork attachments, including Pages, Numbers, and Keynote
Mass email delete
Mass email move
Bonjour service discovery protocol
Support for SVG
Parental controls
Ability to search contacts
App Store (To manage third-party applications)
New Calendar menu in Settings
Updated calculator with extra features in portrait mode, a scientific calculator in landscape mode and an updated icon.
Updated iTunes with a new icon and reordered category icons within iTunes application.
Ability to save or open images from websites in Safari or Mail
Support for Traditional and Simplified Chinese handwriting recognition
Geotagging
YouTube plugin for Safari
Ability to view music videos in Portrait or Landscape view
Ability to take screen-capture by holding Home and clicking Sleep/Wake
Kudos to Wikipedia:
http://en.wikipedia.org/wiki/IPhone_OS_version_history
I can confirm that all the features listed are in 2.0.