[I am CEO of Zooomr]
Well unfortunately it looks like the Chinese government may be censoring Flickr images in China. There are not a lot of details on this yet, but Flickr Chief Stewart Butterfield has issued two comments on a help forum on the matter:
Update from Flickr staff (10:00 PDT, June 7th) : It seems that access to our image servers is being blocked for users in much of China. Our technical staff has looked into this at depth and determined this is not a technical issue from our end. We will keep an eye on the situation and update if we get any developments.
Update from Flickr staff  (01:00 PDT, June 8th) : We are checking periodically to see if the block is still in place, but haven’t detected any change. We hope that this is a temporary issue and we currently believe that it will be. In the meantime, we are investigating our alternatives. Thank’s for your patience,
If you want to follow this case on an ongoing basis you can follow it in this official help thread over at Flickr here.
Earlier this year in March, Digitimes reported on comments made by Butterfield to journalists in Taipei saying that Flickr would launch a version in traditional Chinese by the end of 2007.
China, with the world’s largest population, would seem like a market of interest for most internet companies. Yahoo, Flickr’s parent company, over the past few years has received considerable criticism over their role in the arrest and jailing of Shi Tao, a Chinese journalist who was sentenced to 10 years in prison by the Chinese government.
From CNET reporting:
“We already knew that Yahoo collaborates enthusiastically with the Chinese regime in questions of censorship, and now we know it is a Chinese police informant as well,” Reporters Without Borders said in its statement.”
Update: It would appear that Hamed Saber has built a Firefox plug in that people may be able to use to get around the censorship block on Flickr photos in China.
Update #2: Article from the SF Chronicle.
Update #3: More from Slashdot.