One fairly quick way to check if its a dns problem is to do a nslookup of the site.
On a Mac:
Launch the Network Utility (under applications/utilities).
Click the Lookup tab.
Where it says Please enter an internet address to lookup, enter
www.kitchenknifeforums.com
Under Select the information to lookup, pick Default Information.
Uncheck use dig in place of nslookup.
Click Lookup.
This will show the IP address your dns is showing for
www.kitchenknifeforums.com It should be 64.57.218.150
If its not then your DNS hasn't updated yet and using opendns might be a good option (arguably a good option instead of your ISP's dns but I won't go into the the technical mumbo jumbo =)
You can also try a ping under the network utility to see if you can actually reach the server.