This problem used to frustrate me to, ...
You don't need an automator script to upload to a site, there's a way that's even easier.
In Safari, firefox, or whatever you use get to that point where you have the "Open" dialog.
From iPhoto drag the photo into that dialog.
This is the biggest problem people have when switching from Windows or Linux (it drove me crazy for months) -- Assuming that you have to go through gyrations to find the file that a program is representing. In OSX if you have a draggable object you have the file.
Try this for an example:
Open a terminal window and type "ls " (note the space)
Go to iPhoto and drag the photo into your terminal window.
You'll see it get replaced with the full path to the file.
You can even do this with an open file -- pick something like TextEdit, Word, whatever. Open a file. Look at the title bar, to the left of the filename you will see a little icon. Click and drag it -- you now have a reference to the file location.
You never have to look for a file -- if you want it, there is a reference you can grab.
Once you get used to working with this paradigm you'll start to find things get much more obvious and simple. You'll sit down in front of your Windows PC and start getting frustrated when you drag things around and it doesn't do the right thing.
At least that's what happened to me. But before that I spent a month frustrated always looking for import menus, export menus, file locations. Once you grok the drag-and-drop it all goes away (and, incidentally that's a good reason for using as much OSX native software as possible; X11 applications don't d-n-d nearly as nicely)