Recently (during the last 48 hours) google has changed the image urls from ggpht.com to googleusercontent.com. All images at my wordpress site now show only the file name. If I right-click and select "view image" on top of one of the filenames, I get "504 DNS lookup failed". If I change the ggpht.com from the URL to googleusercontent.com, the image is displayed.
I believe the Picasa and Google Plus Express plugin should be changed so that it would use the new domain.