Perhaps you have , found the solution yourself. Photos from twitter will be shown, but as it says in the FAQ:
Some of the photos attached to my Tweets Are not appearing:
Depending on which service you used to post the photo, you may not be able to see a thumbnail of it on the map. Supported services are Twitter (official mobile app), yfrog, instagram
It works fine for me, I did have problems on one of my web pages, but it was the host, not “Plotandpost …” which caused problems
