Hi there,
Yes, we've been continuing with our investigations today. Unfortunately though we're still some way off a solution.
Our testing has failed to replicate any problem with the web-based uploader. Uploading photos using the Uploadr tool though always seem to fail - this seems pretty consistent with what you guys are seeing.
Similar issues also seem to be affecting Sky and Virgin Media. I've also seen a report from a Comcast subscriber whose been without the service a week or so.
We've cross-examined the traffic at our side and run a few packet captures etc. We seem to be getting a zero size reply to our IWF proxies however this is almost certainly a symptom of the problem and not the cause.
Interestingly, a Wireshark capture shows that the upload completes successfully whilst the tool itself reports a failure (and obviously the pictures are not associated with your account).
I'm beginning to think it may be something to do with routing. I guess we could try and alter the advertised routes for traffic to and from the Flickr servers however there's a number of things that need considering before we can make such a change.