You can share up to 10 photos at a time directly from iPhoto using Messages, a chat application that comes with OS X Mountain Lion v10.8.
To share, you must be signed in to the Messages application. If you have an Apple ID, you can use it to sign in. You can also sign in to Messages using the user name and password for your AIM, Jabber, GoogleTalk, or Yahoo! account.
Open the Messages application.
Choose Messages > Preferences, and click Accounts.
Do one of the following:
Type your Apple ID and password, and click Sign In.
Click the Add button (+) in the lower-left corner of the Accounts pane, choose an account type from the pop-up menu, and enter your user name and password.
In iPhoto, select up to 10 photos to share.
Click the Share button in the toolbar, and click Messages.
A Messages window appears with your photos attached.
Type an address for one or more recipients, or click the Add button (+) and select one or more recipients from your Contacts.
If you want, you can type a text message to include with your photos. You can also add a “smiley.”
Click Send.
A message appears to let you know that your photos were sent.