Tim Watts wrote:

is it impossible to create a link to a
single photo in a Google Picasaweb album?

Can't see any way OTHER than delving into the source of the page, e.g.

http://lh3.googleusercontent.com/-5ySbISGdPYQ/TvQ7QFl7QVI/AAAAAAAAPzk/FiuxGIkDBBY/s400/20090422204726.jpg

Used to be able to with with old Google photos but since getting a Google+
account, viewing a photo is now an Ajax "pop up"...

You can SHARE it with others, but that assumes they're G+ users in one
of your circles.