[Vibrant Android Development] serendipityguy:
Just curious--what do gingerbread and ics offer that froyo doesn't?

Android 2.0

On 26 October 2009 SDK – codenamed Eclair – was released, based on Linux kernel 2.6.29. Changes included:

Expanded Account sync, allowing users to add multiple accounts to a device for email- and contact-synchronization

Exchange email support, with combined inbox to browse email from multiple accounts in one page

Bluetooth 2.1 support

Ability to tap a Contacts photo and select to call, SMS, or email the person

Ability to search all saved SMS and MMS messages, with delete oldest messages in a conversation automatically deleted when a defined limit is reached

Numerous new camera features, including flash support, digital zoom, scene mode, white balance, color effect and macro focus

Improved typing speed on virtual keyboard, with smarter dictionary that learns from word usage and includes contact names as suggestions

Refreshed browser UI with bookmark thumbnails, double-tap zoom and support for HTML5

Calendar agenda view enhanced, showing attending status for each invitee, and ability to invite new guests to events

Optimized hardware speed and revamped UI

Support for more screen sizes and resolutions, with better contrast ratio

Improved Google Maps 3.1.2

MotionEvent class enhanced to track multi-touch events

Addition of live wallpapers, allowing the animation of home-screen background images to show movement

Android 2.0.1

SDK was released on 3 December 2009. It was a minor platform release deployable to Android-powered handsets, including minor API changes, bug fixes and framework behavioral changes

Android v2.1

The 2.1 SDK was released on 12 January 2010. It was a minor platform release deployable to Android-powered handsets, including minor amendments to the API and bug fixes

Android v2.2 On 20 May 2010, the Android 2.2 (Froyo) SDK was released, based on Linux kernel 2.6.32. Its features included:

Speed, memory, and performance optimizations

Additional application speed improvements, implemented through JIT compilation

Integration of Chrome's V8 JavaScript engine into the Browser application

Support for the Android Cloud to Device Messaging (C2DM) service, enabling push notifications

Improved Microsoft Exchange support, including security policies, auto-discovery, GAL look-up, calendar synchronization and remote wipe

Improved application launcher with shortcuts to Phone and Browser applications

USB tethering and Wi-Fi hotspot functionality

Added an option to disable data access over mobile network

Updated Market application with batch and automatic update features

Quick switching between multiple keyboard languages and their dictionaries

Voice dialing and contact sharing over Bluetooth

Support for Bluetooth-enabled car and desk docks

Support for numeric and alphanumeric passwords

Support for file upload fields in the Browser application

Support for installing applications to the expandable memory

Adobe Flash support

Support for extra-high-PPI screens (320 ppi), such as 4" 720p

Gallery allows users to view picture stacks using a zoom gesture

Android v2.3 On 6 December 2010, the Android 2.3 (Gingerbread) SDK was released, based on Linux kernel 2.6.35. Changes included:

Updated user interface design with increased simplicity and speed

Support for extra-large screen sizes and resolutions (WXGA and higher)

Native support for SIP VoIP internet telephony

Faster, more intuitive text input in virtual keyboard, with improved accuracy, better suggested text and voice input mode

Enhanced copy/paste functionality, allowing users to select a word by press-hold, copy, and paste

Support for Near Field Communication (NFC), allowing the user to read an NFC tag embedded in a poster, sticker, or advertisement

New audio effects such as reverb, equalization, headphone virtualization, and bass boost

New Download Manager, giving users easy access to any file downloaded from the browser, email, or another application

Support for multiple cameras on the device, including a front-facing camera, if available

Support for WebM/VP8 video playback, and AAC audio encoding

Improved power management with a more active role in managing apps that are keeping the device awake for too long

Enhanced support for native code development

Switched from YAFFS to ext4 on newer devices

Audio, graphical, and input enhancements for game developers

Concurrent garbage collection for increased performance

Native support for more sensors (such as gyroscopes and barometers)

Android v4.0.1The Galaxy Nexus introduced Android 4.0.1 (Ice Cream Sandwich).

The SDK for Android 4.0.1 was publicly released on 19 October 2011. Google's Gabe Cohen stated that Android 4.0 was "theoretically compatible" with any Android 2.3.x device in production at that time. The source code for Android 4.0 became available on 14 November 2011, three days before the Galaxy Nexus was released. New features included:

Enhanced speed and performance

Virtual buttons in the UI, in place of capacitive or physical buttons

Separation of widgets in a new tab, listed in a similar manner to apps

Easier-to-create folders, with a drag-and-drop style

A customizable launcher

Improved visual voicemail with the ability to speed up or slow down voicemail messages

Pinch-to-zoom functionality in the calendar

Offline search, a two-line preview, and new action bar at the bottom of the Gmail app

Ability to swipe left or right to switch between Gmail conversations

Integrated screenshot capture (accomplished by holding down the Power and Volume-Down buttons)

Improved error correction on the keyboard

Ability to access apps directly from lock screen (similar to HTC Sense 3.x)

Improved copy and paste functionality

Better voice integration and continuous, real-time speech to text dictation

Face Unlock, a feature that allows users to unlock handsets using facial recognition software

New tabbed web browser, allowing up to 16 tabs

Automatic syncing of browser with users' Chrome bookmarks

Modern Roboto font

Data Usage section in settings that lets users set warnings when they approach a certain usage limit, and disable data use when the limit is exceeded

Ability to shut down apps that are using data in the background

Improved camera app with zero shutter lag, time lapse settings, panorama mode, and the ability to zoom while recording

Built-in photo editor

New gallery layout, organized by location and person

Refreshed "People" app with social network integration, status updates and hi-res images

Android Beam, a near-field communication feature allowing the rapid short-range exchange of web bookmarks, contact info, directions, YouTube videos and other data

Hardware acceleration of the UI

Resizeable widgets – already part of Android 3.1 for tablets, but new for cellphones

Wi-Fi Direct

1080p video recording for stock Android devices

If there is anything else that you need, Just ask :D

The data above was retrieved from here