A few weeks ago I rolled out enhanced Twitter Cards support. The algorithm to determine which image to use for the large image cards took a little tweaking, but the results look good (though I think I found a bug in their handling of greyscale PNGs).
Has this led to extra traffic? Well . . . it's hard to say. Posting newsbytes on our social feeds roughly doubles their activity, but they tend to links to sites other than Flayrah, and arguably users now have less reason to visit (the same applies to Twitter Cards). But we're serving our readers better, and that's what matters. Besides, the more useful our feeds are, the more subscribers they'll get, and the more readers for the posts which do lead back to Flayrah.