What Giz said. The CPU's and HD's have built in sensors, even my G4 can read the HD and CPU temps. There is also an ambient temp sensor board Apple put into the G5 towers and later to read incoming air temp.
So, the AP card does not have a temp sensor. Then, how do you get a reliable temp reading from it, or is the widget delivering a bogus figure?
I figure you were replying to the original poster. I'd say the poster misread something. It would be nice if they posted a screen shot to confirm. The card has no sensor I believe, and according to the stuff on the developer's site I see no setting for Airport temps.
And if that's after the machine was running for a while the original poster's card does seem a bit hot. I wonder what a long download would do to the temp.