Yesterday, their tech support got back to me to ask if I used any "special plugins or extensions" with Safari. I told them that I use PithHelmet, but not much else. Almost immediately they told me:
PithHelmet could be the problem. i've added a fix to our code here to try and work around your version number and ignore it. this code will be deployed later today.
And by the end of last night it was working perfectly. I just wanted to post this here because I always appreciate good tech support and I thought it was cool that, because of my whining, all of Flickr now works with PithHelmet.
Also, with the technical problems sorted out and with my new digital camera, I've started using Flickr again more heavily. I'd used it in the past to setup my (semi-defunct) Portland art moblog, but now I set up a profile and am running the RSS feed of my uploaded photos on the sidebar here and am going to see what else interesting I can find to do with it. I'll keep you posted.