Google seems to be testing a new way of checking out a page quickly, without actually loading it, or leaving the search results. This seems to be working only for Wikipedia and only for some users, but it's something Google has been working on for a while now, in various forms.
The mobile web is still slow in many cases, a combination of poor network speeds and slow processors, so anything that can help cut down on the time spent waiting for a page to load is great.
That seems to be the idea behind the Quick View feature. The button shows up next to search results linking to Wikipedia. It loads the page in an overlay on top of the regular results.
The page looks identical to Wikipedia's regular mobile page, so in itself is no way faster than the original page. What could be faster though is Google caching some of the assets and only pulling the actual content from the original servers.