How can I send a multimedia message (MMS) from the Apple iPhone?

One of the most perplexing feature omissions from the iPhone was the lack of support for the MMS protocol. One can only assume that this was a deliberate choice by Apple, though it is hard to determine why. Many users who are accustomed to snapping photos w/ their camera phones and sending those photos to friends and family via text/MMS messaging have been surprised to find out they can't do the