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Update 30Jun2011
Make sure you have a good JetEclair libhardware_legacy.so or libhardware.so as this will enable the wifi in Froyo and later versions of Android. 
libhardware_legacy.so & libhardware.so is hardware specific.

You should only need to replace libhardware_legacy.so if using Cm Spica or Galaxy Tab 1 or SDK version or Android versions with the same hardware.

have not tested the JetFroyo Github binary versions libhardware_legacy.so as this could be a better file. 
Lots of testing needed.

End of Update
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Use this as base example to get wifi working for Eclair to 2.3.3.

Edit your init.rc with the automount + wifi sections.

Use any wifi working kernel you like.

Ginger:
wifi = enable then "turning on ..." message and then nothing.

I had some success with using the eclair "lib hardware legacy .so" but this causes pid issues during start but works.
use only eclair wpa_supplicant.conf with eclair, same for froyo use froyo wpa_supplicant.conf with froyo ect. otherwise you get pid errors.

system/etc/wifi
only needs to have 1 file = wpa_supplicant.conf
the rest can be in 
system/etc