I just came across a reference to Joe Tan's Flickr Post Bar plugin for WordPress. It adds a handy-dandy "add image from Flickr" bar to the WordPress authoring form. You can set it to add any of the standard Flickr sizes. I've set it to use "medium" - the 500px wide image. If it worked, there should be a fun picture of Evan, Teddy, and Daddy playing human totem pole...
It's not quite as cool as the WordPress 1.6 version, but it's here now, and seems to work well.