Hi Chris, NVIDIA hav been very good about this. Strictly speaking the images should not be posted elsewhere. However if you include both a credit that says the image was an entry for NVArt competition and a link back the the competition then you can post to the sites you have.
This is not an open invitation for everyone to post their entry images everywhere. However you can post to your personal web sites, cCGPortfolios or elsewhere here on CGSociety with the proper credits. Please ask before posting on any third party web site.