Actually I live in Finland, and here metal coated thermo windows are common. Unfortunately if I put my cell phone 5 cm outside window, I got full 3G reception and 5 cm inside, it's totally gone. So yes, you can also have metal finish on windows, which blocks signal. It also cause problems to normal FM receiption as mentioned.
I didn't wish for this, because now my wireless (3g) data is over 10 times slower than it would be without that finishing. (3G HUSPA -> GSM 2.5G EDGE)