With the new update to Windows Phone 7, it is once again back to discussions as the new update comes with tons of new features. XDA Developer Forum member has posted a tutorial on how to enable WiFi hotspot on Samsung Omnia 7 and Focus which is previously not available. This mod will allow you to tether through your device, regardless of what your carrier ability to do it with these devices.

Steps to enable Wi Fi hotspot;

1. Remove (uninstall) Network Profile application and remove any APN you set up in settings -> cellular.
2. InterOP-unlock your device (Heathcliff)
3. Install DiagProvXML app
3. Using Isolated Storage Explorer deploy enclosed provxml files
4. Install the xml files in this order: hotspot, hotspot1, mxip_hotspotconfig_01, EnableAutoDataConfig
4b. Check in settings that you can now see Internet Sharing between Bluetooth and accounts!
5. Reboot
6. Deploy WP7 Root Tools (Heathcliff)
7. Now launch Root Tools and go to Local Machine -> Comm -> InternetSharing and manually add:
Name => value (type)
EntitlementURI => ./Vendor/MSFT/Registry/HKLM/Comm/InternetSharing/Settings/OpenMarketEnabled (string)
OpenMarketEnabled => 1 (dword)
8. Clear “CellularConnectionName” (aka set to empty)
and you can go to settings -> Internet Sharing and start it up.

More details available here.