There was this guy arend who made an app for gingerbread that made ad hoc possible on android devices. He pulled it of google play and just updated he wont be dev'ing on it anymore. Read link below and the last answer in the postings/answers.
http://www.arenddeboer.com/wifi-ad-h...r-for-android/

I tried it on my N900 -> nitdroid but couldn't get it to work cause it couldn't mount a certain partition.

Just did a check on the above site to if he (arend) had updated his site/app and found the above mentioned.

Dousan...