z4 Root.. it used to be in the Market i believe.. if not,
[APP] z4root - xda-developers
youll Root, then install the .apk from
Downloads - android-wifi-tether - Project Hosting on Google Code
boom! wifi tether for Free!
for being able to see ad-hoc(say wifi from like a TP2 or something) you need a replacement wpa_supplicant file(attached).. move that using ANdroid Mate or ROOT Explorer to system/bin, paste.. reset.. all good