iPhoto and Aperture users have nice plug-ins to go from their photo management apps directly to Flickr. While we wait for Lightroom’s plug-in architecture, here’s a nifty way to streamline your Flickr workflow.
First make sure you have a current copy of Flickr Uploadr. Then designate Uploadr as Lightroom’s additional external editor. Choose Flickr Uploadr as the post-processing option during Export, and the tool will open with your selected Lightroom images. Adjust your metadata as normal, and send them off.