Gridmarker, the bookmarking engine for Second Life we reviewed here has added support for postcards. Now when you're logged into your Gridmarker account, you can sed a snapshot to go along with your bookmark to pics@gridmarker.com -- Not the most earth shattering new feature by any means, but as Mike who runs the service says, it does mean that you don't have to be wearing the Gridmarker HUD to use the system this way.
I expected great things of Gridmarker, and I still hope to see them. For sometime now though the development of the project has been slowed due to real life work getting in the way of the fun stuff.
Lets hope we see a little more work on this in the future, it's a great service.