[GHFigs]

What if I want to do something else with my photo, that iPhoto doesn't yet have a button for? How does a universal interface look like, that allows arbitrary other apps to get photos from iPhoto?

The email export function is implemented with AppleScript. To add support for Thunderbird (for example) just means writing a similar script for it. Indeed, it appears that someone has already done so: http://softpixel.com/~cwright/programming/iPhoto/

Note that this is a minor hack, to get the button within iPhoto to support Thunderbird. It isn't necessary to get the same function as a regular Scripts menu item. Such scripts can be written in AppleScript, Ruby[1], Python, and Objective-C.

This is not really a solution to the more general problem being discussed, but I thought it worth mentioning.

[1]: http://developer.apple.com/mac/library/documentation/cocoa/C...