It occurred to me that it'd be pretty easy to make a bookmarklet for the recently-launched Google Reader Play:

PlayThis!

All it does is take the current page's feed and display it in the Play UI. You may find this useful when discovering a new photo-heavy site (or anything else with a feed, like a Flickr user page), or when you want to share, star or like an item from a site you're not subscribed to (you can also use the regular Reader subscribe bookmarklet for that).

P.S. If you're reading this in a feed/social content reader, you'll most likely have to view the original post, as the javascript: URL on the bookmarklet link will no doubt get sanitized away.