Until iPhone gets its own ability to send multimedia messages to your buddies, you'll be well served by Quip. This dead-simple, straightforward, and inexpensive iPhone app immediately triggers your iPhone's camera so you can take and send photos to contacts on the spot. Tap the tab and you'll move into library view, where selecting a photo to send a friend takes all of two clicks--after which the quick Quip opens your address book for another speedy selection.
You'll be able to preview the image and add a message by tapping ABC before sending it on its way. Two wishes for future versions: that you're able to send to multiple contacts at a time, and that the technology improves so we can send photos directly, not just a hosted link.