This is a custom build of Ice Cream Sandwich AOSP for the Nexus S.

I have only tested this on a Nexus S i9020t.

Working
- 3G
- 2D/3D HW acceleration (some glitches)
- Audio
- Camera
- GPS
- Face Unlock
- WiFi (wifi patch required for v1, wifi patch not needed for v2)
- BT
- Tethering (new in v2)
- USB (new in v2)
- Data usage statistics (new in v2)
- ???

Not working
- Camcorder
- ???

Kernel
The kernel is custom build from the aosp source (same as stock 2.3.7) with the following changes:
- mxt224 patch to make touchscreen work (source patch)
- pvr-driver backported from aosp tuna kernel (source patch)
- v2: bcm4329 parameter backport (source patch)
- v2: android usb gadget driver backported from aosp tuna kernel
- v2: xt_qtaguid and xt_quota2 backported from aosp tuna kernel

Other kernels will not work unless they include the patches above

Notes
- device config for this build - source code
- pvr updated to 1.8 from omap-tuna kernel - kernel patch
- imgtec drivers from maguro - drivers
- mxt224-patch from syndtr - kernel patch
- audio and camera library from beezy's ics sdk port
- gapps from paul's leaked ICL23D dump

Changes in v2
- Optimized binaries (user build)
- wpa_supplicant switched to 0.8, should fix status icon and hopefully more
- Tethering over wifi and usb
- USB mass storage
- Data usage statistics
- Updated Maps, Music and Google+
- Updated kernel to support usb, statistics and wifi tethering
- Note: Camera icon on home screen is not working, remove it and add it again

Download Nexus S - I902X (Use at your own risk!)
v1: here (wifi patch)
v2: http://www.multiupload.com/00F7ELOHQM (no need for wifi patch)

Download Nexus S 4G - D720 (Use at your own risk!)
v1: here (wifi patch)
v2: building