I've been using LR3 since the first Beta, and am really pleased now that the final product has come out. One of many great features is the direct and somewhat dynamic link between LR and Flickr. I've uploaded over 200 images to my Flickr site that way. However, there is one thing to be warned about if you use the links to your Flickr images themselves. Let me 'splain.
If you go to something like this: http://www.flickr.com/photos/wolfnowl/4686813509/
you'll end up at Flickr's page for that image. However, sometimes I use my images for my blog posts, and for that I go to the URL for the image itself, which looks more like this: http://farm2.static.flickr.com/1299/468681...1ffe0f012_o.jpg
. Thay works fine, but... if you change the metadata or for some reason Lightroom finds it necessary to "Republish" the image, Flickr's page for it will remain the same but the URL of the actual file itself will change and you'll end up with dead links in your blog post. I found this out the hard way. The obvious answer of course is not to upload images for a blog using the dynamic links in Lightroom but to do it the old fashioned way. You lose the dynamic functionality like having LR download comments into the catalog, but it will save you trouble down the road.