Are there any tools available (web tools, PC tools, iPhone tools) to send an MMS to the iPhone which contains images and text?
Have you tried sending via email? I think all carriers have an email formatted address for their phone numbers. Here's a random Google result with quite a bit of info:

http://forums.macrumors.com/showthread.php?t=507548

Based on the comments, it appears to work with MMS, not just SMS. There's also a few services suggested, there.