It's something that you can do with any cheapo netbook and any cheapo phone
Any except Apple! Nothing new here. I got the iPod touch way back and really liked it except it stopped working as soon as out of wifi range.
Very frustrating, when I had a 3G phone in Bluetooth range.
Easy solution: ditch the iPhone (you don't need it now that you have an iPad to look cool and run those must-have app's), get an uncrippled phone with wifi, and run a wireless access point on the phone.
e.g. Joikuspot on Symbian or Maemo. Some WinMo phones have it built-in.