Well it seems like PostImage is indeed having problems and it looks to be about its Domain .ORG It looks like you may be able to see your own posted pictures but not those of others. If you 'Right Click' the Image Link you see and select 'Open Link in New Tab' then in your Browsers Internet 'Address Bar' change the Postimage.ORG to Postimage.CC you should be able to view the images. You could also change your own pictures by editing your Posts and making the .ORG to .CC change yourself to have your pictures work in the Forums. It should also be noted that all new pictures posted through PostImage already has the Domain change made so they won't nee the change.
But hold on for now....There may be a way for the whole site to be changed to reflect this change in a Batch correction so we will check with our Technical Team of one, Thehsvdude. Hopefully this will work and our Members can rejoice.
Here is a Link to an outside Forum and what they found out contacting PostImage... http://vintagecaravans.proboards.com/thread/17088/postimages-org-website-available?page=1