Last summer, I tried to survey the landscape of software available for uploading photos to Flickr on Ubuntu. My conclusion at that time was that there were no good options that met my needs-- which I felt were fairly modest:
2/24/11 UPDATE: The recent release of Frogr 0.4 makes this post obsolete. It's the Flickr uploader for Ubuntu I've been waiting for. It does everything I was looking for, and more-- I highly encourage anyone looking for a Flickr solution on Ubuntu to go download it.