Be warned: We can not be held responsible for any damages you commit to your devices. Proceed at your own risk.
I have managed to find the secret combination of AT commands  that will allow you to save an incoming message to the SIM card and then you can read it on the iPad.
You will need the following commands in order to receive SMS to the SIM card.
You can make use of the sendmodem  code to make life easier. You can use minicom too!
There is an awful time out issue. To start this process you will need to run ‘./sendmodem at’ until you get OK and then quickly send the rest of the commands. I have hacked away on the original sendmodem to include all the above commands in one executable. Will post it later on.
Also, once you have reached the maximum number of messages you will need to start deleting them. More information in later posts.
 – GSM AT Commands example (good ref really) –http://www.arcelect.com/GSM%20Developer%20Guide%20-%20GSM%20AT%20Commands%20-%20Rev%20%20A.pdf
 – sendmodem – http://code.google.com/p/iphone-elite/wiki/sendmodem