It’s always a pain in the rear when a friend sends you a link to a photo or video when you’re in the middle of doing something and you don’t want to take the time out to open the link in a new tab.Google decided the pain was too great to force those using Gmail to have to do that one moment longer, and users now can get previews for YouTube videos, Picasa or Flickr pictures or Yelp ratings right there in your e-mail.In Google Labs, you can enable the previews for any or all of the services in your e-mail. For