Latest community website don't build on web. They build on mobile.
Users register, access through mobile platform (iPhone, Android). Store photos at third party website like flickr, Instagram... Status and blog through twitter, finally publish to Facebook.
Users may not need to access to the website. A few good examples of the new mobile community website will be Whatsapp, Viber, Instagram (and more will come). Location base website like Gowalla and foursquare has a web version, but most of the time, users access through the mobile platform.
Whatsapp is a mobile application (available on iPhone, Android and BlackBerry), allow users to send SMS (to another mobile application) for free. Viber is the audio version of Whatsapp. Both application register through mobile platform, access the contact list and build a community.
Instagram is a photo sharing community on iPhone. You take a picture, add a filter to it, and share it out through other community website like flickr, facebook, twitter and etc.
Everything just done on mobile application, cooperated with other website to build a bigger community. New community website don't really need a website access anymore.