Don't know if it's been pointed out yet, but I see that if you "share" pics from your camera roll, they seem to get downsized to 800 x 600. However if you copy and paste the pics into your email, they get sent full size.
This is actually pretty lame, but I'm glad I know it now.
I confirmed that if you email from the photo roll, either by selecting one or many it does indeed shrink them. The only way to email full rez is by copy/pasting it into the email.