For some reason, the experimental feature is no longer available. The blue button is missing and Wikipedia articles are loaded just like any other search results. Maybe it's a temporary issue.
The Quick View sign-up form is still available. "Mobile quick view is an experimental new project that makes websites appear almost instantly (around 100 milliseconds) after you click on a search result. More and more people are searching on the mobile web, and we will continue to work together with webmasters on making it faster and better. Sign up below to get updates about participating in the mobile quick view field trial," suggests Google.