The iPhoto 9.1.1 update fixes this issue but you must navigate to iPhotos preferences after updating to do so. in iPhoto '11, go to iPhoto's Preferences and select General » Email photos using: and choose Mail or whichever other email client you use. Now when you select Share in iPhoto, you can select the file size you wish to send and compose your message in you favorite email client.
[crarko adds: I tested this, and it works as described.]

