Windows Mobile 6 devices offer Internet Sharing feature for Bluetooth and USB. It works in this way that you start Internet Sharing application inside of your Windows Mobile phone and then other devices can share the Internet connection. What if you could fool Windows Mobile phone and instead of Bluetooth use WiFi? Would it be possible? Yes, it is:
I have figured out how to use Internet Sharing over WiFi, which essentially makes my Hermes an Access Point.
Do the following:
1) Open Settings->Internet Sharing. Enable IS for Bluetooth PAN.
2) Change HKLM\Comm\ConnectionSharing\PrivateInterface to "TIACXWLN1" (it should currently be "BTPAN1").
3) Open Settings-> Connections -> Wi-Fi. Select Network Adapters tab. Click IEEE 802.11b/g Compatible Wi-Fi.
4) Enter IP address 192.168.1.1 and subnet mask 255.255.255.0. Click OK.
5) Select Wireless tab. Add New.. to add the Network name for your ad-hoc network (I prefer "adhoc"
6) Set the client computer to use the same ad-hoc network. Client will receive an IP address from the device (don't need to manually set the IP).
To learn more, click here. Screenshots and further information can be found here.
Conclusion: hopefully Microsoft will built-in in future into Windows Mobile platform, but for now this amazing new feature becomes available with a hack. While connection sharing over Bluetooth is also wireless, it is limited in distance and number of devices handled, but with Internet sharing over WiFi any Windows Mobile with WiFi can become a WiFi access point - what is much more versatile kind of Internet sharing. Since many notebooks nowadays simply don't support Bluetooth but WiFi is now built-in even in cheapest models, this solution may be extremely usable for travellers, who posses a Windows Mobile phone! People who claim that built-in WiFi is not a must-have feature in Windows Mobile phones have been proved wrong.

Source: msmobiles.com

Taimur Asad (The Microsoft "Wow" Blog!)