While there are plenty of user interface changes (we'll get to those), some of the more esoteric back-end changes are also the most impactful to the Gingerbread recipe, especially those that will boost mobile gaming and make two-way video chatting open to all.
On the gaming front, for example, developers will be able to directly access Open GLS and audio, and take advantage of Gingerbread's gyroscope support to create slicker, faster-moving games. Android 2.3 also offers developers VoIP via SIP, which translates into the ability for application authors to easily build two-way Internet video calls into their apps.
In multimedia, support for the WebM video compression standard that Google spearheaded may play a role in setting standards for high-definition video playback. WebM makes it possible to play videos hosted on YouTube or other Web sites from the Android browser.
Near field communications (NFC) is another notable enhancement. An onboard NFC Reader application will be able to scan NFC tags. In a typical scenario, you would scan an NFC tag with your Android app for a shortcut to a Web site whose URL is embedded in the tag, according to Google. This is similar to what you could do with a QR code, except that NFC also requires some hardware compatibility (think Bluetooth). The Nexus S will have an NFC chip baked in. (For an example of one implementation, check out our hands-on field test of an NFC payment solution.)
Back on the interface side, Android 2.3 users can expect to see a multitouch virtual keyboard for quickly entering symbols with on-screen keyboard shortcut combinations. If you make a mistake, Gingerbread will let you switch to voice mode to make a correction. Google has also revamped its text selection workflow to make it faster to get at text with just one touch (in Android 2.2, or Froyo, you touch and hold a word to start selecting text).
We also welcome the new camera feature that lets you shoot and record video of the front-facing camera, not just the the (higher resolution) rear-facing camera.
Theme and user interface touch-ups
Redesigned virtual keyboard with different font
Switch to voice mode to make text corrections
Multitouch capabilities to enter keyboard shortcuts
One-touch text selection
Power manager closes some CPU-hogging apps
More accessible power management app
Internet calling via SIP
NFC (near field communication) support
New download manager
Access to front-facing camera from camera app
Enhancements for game developers
API support for sensors including gyroscope, gravity, and barometer
New audio effects for developers, including sound mixing
Support for VP8/WebM video compression
Camera API access for developers
You can read up on even more details in the Android 2.3/Gingerbread SDK highlights and in the release notes for developers. As for when you'll get Gingerbread over-the-air on your Android phone, here's what we know.