Starting with the latest Mapviewer kit (10g patch 5, a.k.a 10.1.3.3 for WebLogic), you can easily display an external GeoRSS feed as a FOI layer on top of your tile layer. In fact, your MapViewer installation comes with some GeoRSS tutorials, such as tutorial #58. Its full URL is http://<host>:<port>/mapviewer/fsmc/tutorial/samples/georss-demo.html.
That page displays the United States continental states. Below the map you will see a text field where you can enter a custom URL to some external GeoRSS feed. If you want to see a feed that contains pictures (who doesn't!), you can try this Flickr photo stream feed:
(My colleague Jayant sent me this feed so you will have to ask him why this particular feed is chosen).
You will see a map like this (after zooming into the San Francisco city area):
Note that if your MapViewer is running behind a firewall, you will need to setup the web proxy stuff in mapViewerConfig.xml (check the User's Guide on instructions).