Nokia Poland shows off double height live tiles in their promo video for Lumia devices running Windows Phone 8.1. Looks like we'll get it very soon
Check 0:50
https://www.youtube.com/watch?v=EP7PukuEYoQ#t=61
Check 0:50
https://www.youtube.com/watch?v=EP7PukuEYoQ#t=61