Here's a complete list of the new iOS 4 features:
1. Multitasking
2. The records of icons
3. The discussions in Mail
4. Inbox mail account with several
5. Ability to have multiple Exchange account
6. The photo of the contact in a mail
7. The game center
8. Create playlist in iPod
9. Remove the iPod playlist
10. Wallpaper SB editable
11. Sync notes with MobileMe, Gmail …
12. Photos.app is compatible with the landscape
13. Manages Photos.app events
14. Manages Photos.app faces
15. Manages Photos.app places
16. Count of characters in SMS
17. Password lockscreen with anything other than 4 digits
18. Push locally
19. Calendar displays birthdays
20. Spotlight search on the WEB
21. 5X zoom in the camera
22. Management of IPv6 in WiFi
23. Support bluetooth keyboard
24. New animated icons when unlocking
25. Bars iAd
26. iBooks Store
27. Auto focus in videos
28. Icon of the service location in the status bar
29. Suggestion for the spellchecker
30. Resizing when sending a photo
31. Rotating a photo
32. New albums in iPod format
33. New calculator icon
34. New icon Dictaphone
35. New Dock
36. SSL VPN
37. Place a landmarks on maps with a long press
38. Search SMS
39. The new positions of the accents on the keyboard
40. Choose the order in international keyboards
41. New record of creating a new contact
42. Deleting messages after search
43. Adjusting the police alerts, calendars, messages and notes
44. Importing contacts via an account CardDAV
45. Remove the marking applications while removing
46. Suggestion Google in Safari
47. When browsing the Springboard, suppression of light “bouncing” icons
48. Slightly modified Weather Icon
49. Camera Icon slightly modified
50. Notes Icon altered slightly
51. iPod icon slightly changed (adding a very slight relief)
52. Icon Award slightly modified (lighter down)
53. Icon Clock slightly modified (Dial larger)
54. Enable or disable tracing, adjustable per application
55. Display the site title in the history in Safari’s address bar
56. Deployment of wireless applications for businesses
57. Safety Messages for businesses
58. Accessibility: Enabling the utterance corrections suggestions
59. iPod: Whether to info on the songs and lyrics
60. Direct link to the calendar on a date (for the link as such, mail, web site addresses from a mail …
61. New representation for the icon location
62. Overview of a file attached to an email
63. Safari: The button “Google” rename “Search”
64. Move emails to another address
65. More button with direct link from Compass Maps
66. Mobile Device Management for Business
67. Support for Exchange 2010
68. More delete button for email archiving but
69. Spotlight Search Wikipedia
70. Assist Internationnal: U.S. prefix number
71. Now shows an area Spotligth “Best outcome”
72. Mail now supports aliases.
73. Play YouTube videos from Safari
74. Safari: Remembers the last folder when adding bookmark.
75. Whether to Cell Data
76. Select the shape of a given language keyboard (Azerty, Qwerty ,…
77. Contact: Relation to a new contact
78. Spotlight: Search SMS
79. Provide an application from the AppStore
80. Spotlight: search with the name of the publisher.
81. Open a file with a dedicated application for mail
82. Wifi persistent even in standby
83. New on Nike +
84. Support for Braille voiceover
85. Accessibility: Alphabet Radio
86. Accessibility: Change your
87. New language for voice control: Danish.
88. New keyboard: Cangjie (Traditional Chinese)
89. New keyboard: Wubihua (Chinese Traditional and Simplified)
90. Change keyboard by holding down on the earth
91. Play video in portrait mode in YouTube
92. SMS icon on the failure message when sending an SMS
93. The iPod controls now in the Dock of multitasking
94. Locking the screen orientation
95. File Sharing on iTunes
96. Link to the calendar to create an event from an email by clicking on a word like “Tomorrow,” “Evening”, “Noon” …
97. Presence of a small + on iTunes as indicating that the application is compatible iPad
98. The icons have a transparent background, have a black background on the AppStore
Source: MacHackPC.com