When embedding or sharing a photo, it would help to be able to specify a default focal point, i.e., specify the object in the composition that is in focus when first viewed.
It seems to me that the most intuitive way to do this as follows: Whatever focal point is last set while logged in at pictures.lytro.com/user should be the focal point that passes through to any <iframe> embed or other share of the photo. You could even make it clearer by asking the user to specify whether the currently viewed focal point should be "locked" and passed to embeds/shares.
The iPhoto equivalent is that it allows you to specify which photo in an "Event" will be the "Key" photo. Here, you should allow your user to specify which "focal point" of a photo in a story will be the "key focal point" that carries through to any embeds.
As an in-use example, on www.nyny.info I might want the "Chrysler Building at Night" photo (mouseover the dots to find it) to default to Chrysler Building in focus, Plant out of focus, rather than vice-versa.
Please let me know if you need more clarification.