You're right. Apple iPhoto has hooks built into it that let you publish your photos a wide variety of ways, from print books to Mobile Me, Flickr, and Facebook. Darn helpful, but as with any of these sorts of connections, you do, of course, need to start by making sure you have an account set up on the particular service you want to use.

I'll assume you have a Flickr account set up, but if you don't yet, then you need to sign up for your free Flickr account.

Done? Great!

Now let's get to it...

If you launch iPhoto and then look on the lower right corner, you'll see:

In this case we're going to export some photos to Flickr. To do that, you need to first select some pictures. Either use Command-Click to select the specific photographs or click on an album or event to grab everything therein.

Since it's the first time you've done this, Mac OS X iPhoto will double-check that's what you really want to do:

Yep, that's what we want to do. Click "Set Up".

Now you'll need to sign in to your Flickr account (aka your Yahoo account):

Once you sign in you'll be asked to give "iPhoto Uploader" permission to access your Flickr account:

That's what you want to do, so pick the right option, not the left, because you did actually ask iPhoto to connect to your Flickr account. Click "Next".

Yeah, yeah, that's cool. Keep going...

Here's where I found it a bit confusing because I closed the Flickr window and nothing happened for a few seconds. Eventually, however, iPhoto figured out that something had changed and replaced the "Connect to Flickr" warning with the following photo publishing configuration window:

If that configuration works for you, proceed. Otherwise, you might poke around at the options here to see what you can change and fine-tune. I generally publish photos that are only for my family and friends, but in this instance, I uploaded a few pictures from Seaworld San Diego to my main Flickr account.

Once you've configured things, it'll start uploading the pics themselves:

Note that there's a (small, sorry) progress bar on the top right. It didn't take long with my pictures, so just have patience while they're all sent up to Flickr.

Eventually, they'll be done and you'll notice on the left column in iPhoto itself there's now a Flickr album that parallels what you've uploaded:

Cool. And those pictures? Check out my photos of Seaworld, as uploaded directly from Apple iPhoto.

It's really easy.