Following steps  are needed for ICS Android application Development Setup :

1.Downloaded the JDK7 and installed it in machine
2.Downloaded installer_r20.0.3-windows.exe from google site
3.Run the "installer_r20.0.3-windows.exe"
4.Followed the below blog to download ICS SDK
http://www.android.pk/blog/tutorials/install-and-run-android-4-0-sdk-and-ice-cream-sandwich-on-pc/
Now ICS SDKs are installed.Create the AVD for for any platform which requires for application development
5.Downloaded ADT plugin from google site
6.Downloaded the Eclipse classic
7.Downloaded the android_sdk_for_windows.zip and set the tools/platform-tools  folder in PATH variable
8.Installed & Opened the Eclipse classic application
9.In Eclipse, Select    Install new software & select the localpath and add the ADT plugin zip file &
install the files
10.After the ADT plugin was installed, eclipse showed that it requires android support libraries...I installed that android support libraries too...


11.In eclipse->Preferences->Android->SDK location as "android_sdk_windows" folder path.
12.create new android application in eclipse
13.To run the application in emulator,
In Eclipse, Select Run->Run Configurations->Give Some string in "Name" box and select Launch default activity.
 In "Target" tab,select the AVD configuration to run the application

Changes/Features in android  Icecream sandwich:

1.RTSP streaming was integrated with NuPlayer
2.Valgrind  static memory leak tool is ported to android
3.gdb is ported to android
4.OpenCV image processing library is ported to android that is why facedetection / recognition is possible in
ICS . Samsung S III ICS is having face detection functionality
5.OpenAL application layer support  [refer system/media/wilhelm folder path]
6.Subtitle support through TimedTextPlayer for video/audio playback
7.ION memmory manager support in ICS
[ ION is a generalized memory manager that Google introduced in the Android 4.0 ICS (Ice Cream Sandwich) release to address the issue of fragmented memory management interfaces across different Android devices. There are at least three, probably more, PMEM-like interfaces. On Android devices using NVIDIA Tegra, there is "NVMAP"; on Android devices using TI OMAP, there is "CMEM"; and on Android devices using Qualcomm MSM, there is "PMEM" . All three SoC vendors are in the process of switching to ION].
More about ION memory can be found : http://lwn.net/Articles/480055/
8.Framework for DRM
9.NuPlayer is introduced for HTTP live streaming in Honeycomb tablet. In ICS,  RTSP stack/streaming is removed from stagefright and integrated into NuPlayer
10. There are two ways to integrate the decoders in gingerbread
        i) Software decoder path [google decoders are integrated by deriving from MediaSource.InstantiateSoftwareDecoder() function is used within OMXCodec.
        ii) OMX path
       
  From ICS onwards, Google decoders are integrated in OMX Path and InstantiateSoftwareDecoder() is removed in stagefright