This is the first time patching infrastructure introduced in WildFly 8.0.0 can be used to update WildFly. So you can either download a full install of WildFly 8.1.0, or just the update to 8.0.0. This video explains how to install the update in offline mode (server not running) and online mode (server running).
UPDATE: The patching mechanism is supposed to be used for our products (JBoss EAP etc.) to deliver a stream of bug fixes, while the community projects (WildFly) will be used to primarily deliver feature updates (and fixes of course, but the emphasis is on the updates). So WildFly will provide “patches” and future versions of JBoss EAP will provide “patches”.