A plugin for iPhoto exists that extends the range of email clients you can use to email photos from iPhoto, but nothing so far plugs that gap for webmail services.
Juan Leon stepped up to the challenge. He has produced an iPhoto plugin 
that uses Gmail to send photos.
After you install the package, you will find a new pane in iPhoto’s Export menu (File > Export in iPhoto 6, Share > Export in iPhoto 5):
The only possible pitfall here are the options for sizing the images. If the image you want to send is less than 800 pixels in width or height, the plugin enlarges it to that size. In that case, just select “Send original”.
Juan says that the plugin “is still a very early piece of software, probably has many bugs, and is rough around the edges”. I emailed a dozen photos of varying size and format tonight and it seems to work fine.
The resulting emails look good:
He welcomes constructive criticism at the email address you can find on his web page where you will also find the plugin, which is donationware.
Nice tip! What about the picture of the kid with the mouse as a cell phone? Is it available in Flickr? Thanx
I don’t remember where it came from originally. I think it was in a blog post about WWDC earlier in the year.
The title of the photo is “Mac Telefono”. Spanish?
Does it integrate with Address book so you can add a group that will send to multiple email addresses?
Hey guys, thanks for the nice comments. I’ve been on vacation and hadn’t seen any feedback until today! I’m quite glad that others have found the plugin useful. I’ll try to roll out some website changes to reflect known bugs and keep track of feature requests, etc.
Juan, your website is not available anymore!
Looks OK to me. Are you still not seeing it?
Yes, unfortunately I can’t see it yet.
The website is hosted at home and I use domain forwarding. Perhaps the forwarding is being stopped by routing/firewalling software on your end. Please contact me: the email jils.i2g____at_symbol____ gmail.com to try to troubleshoot.
I’d also like to mention that Gmail Contact list integration is currently under development for the next release.
Juan
dear dear, you can actually see the damage the radiation from that mobile phone is doing to the side of this poor child’s head :)