[nitrous9200]

Two ways I know of to do this, either the Microsoft Internet Sharing or WMWifiRouter. Internet Sharing is not built into the stock software that comes with the Omnia, so you'd have to download it separately - but that requires ActiveSync and IDK if there is a linux workaround.
WMWifiRouter turns the phone into a Wifi hotspot that your laptop and anything else could connect to. That also requires internet sharing to be installed, but you don't need Windows on your laptop since you're not hooking up to the pc. You would either need to flash a cooked ROM (most, if not all, have this built in) or install IS manually; I think there's a thread in here somewhere. Second thing, WMWifiRouter is no longer free, but if you search around you can find an older version that will work.

I use the wifi hotspot method and that works great, though you may want to remove any case you may have on the phone and even take off the battery cover and flip the phone screen down, because it can get very hot using this application!