I've managed to make mine working, but there's always a BUT.
Card is recognized and is making search for wireless networks available and shows them, BUT these drivers only conect to networks WITHOUT security. This means that only free wireless's will work.
How to install:
Go to http://code.google.com/p/iwidarwin/
PROSet/Wireless 3945a/b/g OS X 10.5 SVN latest
now, on your MAC, do the following:
Install the .pkg and when it tells you to press restart DON'T DO IT right away. Wait a minute because Leopard will recognize the card and ask you to go to network preferences. When that happens, press APPLY in network preferences.
Now you can reboot.
DON'T TRY TO OPEN THE UTILITY TO WORK WITH THE WIRELESS CARD YET.
After reboot, go to disk manager and make a permissions repair action. After that, reboot again.
Now you can go to Applications folder and start the NetworkSelector app.
Enjoy your wireless device.
I can only confirm this working in Leo 10.5.5 using distro iDeneb v3 10.5.5.