Entryexpress.net is one resource where you can find information about upcoming field events.
The 2010 Central Regional Specialty will be in Minnesota in August. It will offer a WC/WCX.
If you're interested in Field Events this would be a good trip to make. The GRCA offers the WC/WCX mid week and NFHRA offers an AKC Hunt Test on the same grounds beginning two days later. Double header Junior, double header Senior and a Master. I'm lobbying for and O/H Qual too but the jury is still out on that one.
So if you were to have a good weekend you could pick up a WC/WCX and a couple of AKC Hunt Test Passes in one trip.
Entry Express has some... You can also look for Flat-Coat tests as the requirements are the same, Goldens can get a GRCA WC/WCX at a Flat-Coat test... There was just one here, but I don't see much else listed. I would try to contact local Golden and Flat-Coat clubs in the area and see if they have anything in the works...
Keep checking back at the GRCA WC/WCX listing periodically. As clubs get their events approed they will be listed there. I find that there are usually more as spring approaches.
The WC/WCX in the US is a club title as opposed to an AKC title. This means that you get a certificate from the GRCA but the title will not appear on the pedigree. In Canada, the WC/I/X program is run through the CKC so will appear on Canadian pedigrees!
Aside from the details everyone else has posted, I would add that the major difference between the WCs and hunt tests is in the way the scenarios are set up. For the WC you will have gunners wearing white and standing out in the open. As in a field trial you can come to line and show your dog each gun station and cue them. (And there is an honour in the WCX--it is on the water marks.)
In a hunt test you may not point the gun stations out to your dog. There can also be many of the elements of an actual hunt, including multiple decoys, and factors of terrain you might encounter when hunting, such as lily pads and logs. Gunners can be hidden, and the marks can be quite a bit longer and more complex than what you will see in a WC. Sometimes people get upset as they think a judge has made a JH mark too tough, but I think it is important to keep in mind that the dog should be able to handle as singles the type of marked retrieves they might encounter on a regular days hunt. Dogs need to be trained and experienced with a variety of situations.
The other thing you should do is get yourself a copy of the rules. READ THEM!! It is the handlers responsibility to know what can be asked of their dog, and what they may and may not do on the line, and nothing is more frustrating as a judge than having to drop a dog because their handler did something that requires a failure. I have seen people cry (yes, cry) and whine and play the "But I didn't know" game--not pretty.