There are couple of applications for SMS spoofing that work quite well, but no one made one yet for iPhone...

Here is one, for Palm, made in JAVA I think... Someone might be able to port it..
SMS spoof

And here is a Linux program:
Index of /download/smsclient-3.0-testing
(download version 3.2)

Once you install it, you need to patch it with this:
http://overet.securitydate.it/stuff/...0.2-patch.diff
and now you can send spoofed SMS messages..


There is also another patch for SMSClient app I found, which will let you spoof SMS meessages:
http://www.s0ftpj.org/tools/ucp.c

I am posting these tools to help any interested developer in understanding how to spoof messages, that's all..

Aight, I did my part