If you want to give it a try,
* Install the perl module Flickr::Upload using either CPAN or download from http://search.cpan.org/~cpb/
* Grab this script
* put it in your ~/.gnome2/nautilus-scripts directory
* edit the following lines for your own use:
my $FLICKREMAIL = 'firstname.lastname@example.org';
my $FLICKRPASSWORD = 'somesekretword';
my $FLICKRTAGS = 'i like traffic lights'; # space separated list
It works find on my debian/sarge laptop, but should work fine on any other gnome desktop.
Patches would be welcome.