RWL,
The state of Illinois does not honor
any other state's permit.
There is provision in the law for those with permits who are transiting the state to carry while in their vehicle, but I don't know of that law being tested yet.
Like TLee says, pay your money, take your chances. LEOs from all over Illinois have been arrested and jailed for carrying in chicago. This is not internet rumor, as I know a couple of them from our local sheriff's office.
This
MAP gives a pretty good idea of where a guy can carry with the permits he has. Click on the state your permit is issued from.
