All screenshots have been taken and uploaded thanks to justinomg over on MacRumors Forums.
• You can now pause apps by clicking the icon while it downloads/installs.

• Tripple clicking the microphone button (attached to included
headphones) now goes to the previous song played/in a playlist. (Credit
to Sealit).
• New podcasts & videos had “filled” blue bubbles next to them to
indicate that they were new, but with 2.1, if you have “half-played” a
podcast or video, it will include a half filled blue bubble. (Credit to
Dangeresque).

• Sound from videos now “fade out” if you press the home button. Before, they would cut out abruptly. (Credit to Dangeresque).
• Options to load & display earlier text message in a convosation. (Credit to cx300).

• The iPod now shows the album artist and album name underneath the song title.

• New 3G, Edge & GRPS icons

• EXIF data infomation now remains on photos/pictures when emailed from
your iPhone. Sites such as Flickr are now able to show geotag and other
infomation. (Credit to MadGoat).
• Updated apps now keep there original position in the Home Screen.
• Although it isn’t exactly a “new feature”, some bluetooth headsets
which didn’t originally work with visual voicemail on previous firmware
versions have been reported to be working on 2.1.
Confirmed headsets:
• (Model number unknown) Platronics BT Headset (Credit to Trihard).
• Plantronics 520BT Headset (Credit to trunksu).
• (Model number unknown) Motorola BT Headset (Credit to MisterBlister).
• Plantronics 925BT Headset (Credit to diesel).
• Plastronics Voyager 510BT Headset (Credit to QuarterSwede).
• Bluespoon AX2BT Headset (Credit to galenmd).
• The 12/24 hour clock which has been available in previous versions is now usable to UK iPhone users.


• iTunes now displays how much infomation is taken by up applications installed on your iPhone.

• The Camera application can now be restricted from Settings. (Credit to Kardashian).

• Auto rebooting once the Apple Boot logo dims fixes the “ALoD” issue. (Credit to Switz123).
• iPod volume setting is now independant to the phone ringer volume setting. (Credit to Rat-Boy).
• When location services is switched off in the Settings menu, the Maps
application reminds you to must manually turn it back on from the
Settings menu when using GPS. Originally, you would have the option to
turn it on when the notification appeared. (Credit to sgiles1).

• More infomation is provided for audiobooks, such as displaying time left in active audiobook. (Credit to reposed).

(Credit to reposed).
• When recieving a text message, it used to display “Sender - Text
Message” when the message preview was off, e.g “Pete - Text Message”.
After updating to 2.1, it now just displays “New Text Message”. (Credit
to nutts & phannon666).
Screenshot to be added soon.
• You can now display the AM/PM on the lock screen, if you’re using the 12-hour clock.
Note: This function, for some reason, does not appear on
everyones phones. Some ‘upgraded’ phones show the AM/PM indicator when
set to 12-hour, but some don’t. However, most ‘clean installs’ of 2.1
will show the AM/PM indicator. (Credit to Kardashian).

• Third-party application settings are loaded after loading the main Settings. (Credit to Nall).

(Credit to Nall).
• With the UK English keyboard setting, when entering URLs, holding
down the ‘.com’ button would bring up shortcuts to other TLDs, but for
some reason it would drop ‘.net’ to make room for ‘.co.uk’. 2.1 adds
‘.net’ for the UK English keyboard. (Credit to NekoFever).

(Credit to NekoFever).
• Apple have fixed the grammar in the App Store when all apps up to
date. Prior to 2.1, the update page would display the text “All Apps
Are Up-To-Date.” (hypenated with a period). The update page now
displays the text “All Apps Are Up to Date”. (Credit to NekoFever).

(Credit to NekoFever).
• Double tapping (the standard gesture for zooming) didn’t work in
prior firmware versions in the Mail application. The only way to zoom
into content (e.g. a HTML attachment/web page) was to use the ‘pinch’
method. 2.1 now adds the functionality of double tapping to zoom in the
Mail application. (Credit to sibruk).
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“Genius” playlist creation screenshots:

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