I don’t know if it is against Flickr copyright policy or not but there is a freeware available which allows you to download all the photos from a Flickr account.
According to the site, the software can automatically download the best available quality for a picture (like – original, large, medium). It also claims to download “protected” images that are placed below the transparent “spaceball” area.
You can download the installer here.
Please install the software at your own risk and I am in no way associated with the developer. I found the program in the internet while surfing and sharing it in the blog for the people who might want to use it. I haven’t tried it myself, please comment if any of you tried it.