Google's Safebrowsing Diagnostic page reveals nothing even remotely helpful, other than it apparently doesn't contain any malware nor has it distributed any.
We're trying to sort it out but there isn't really any information provided by Google/Chrome to go on. The best "details" they have show that Twitpic has 0 pages with Malware.
Crazy how some automated process at Google can kill an entire site just like that.
Yea, it actually renders twitter.com somewhat unusable too, since they show twitpic images in profile pages (meaning those profiles are also blocked by Chrome).