The NIC itself can only do it for what the firmware is programmed for. For most consumer-grade NICs, that’s going to be a magic packet. It really has nothing to do with networking layers as the WOL-enabled NIC would be using layers layers 1-3 just like the router.
Apple recently expanded the WOL functionality in Snow Leopard to allow the OS to hand off Bonjour services to the Apple Airports. This is what your friend is talking about. Basically OSX tells the router that it’s going into WOL mode and the router memorizes what services that computer was making available and continues to broadcast them as available. When another computer wishes to use one of the services, the Airport sends a magic packet to the computer, waits X seconds, and then forwards along the service request to the computer. This is something that has to be made available at the software level and the router has to support it. AFAIK Windows 7 doesn’t support anything like this and I don’t imagine custom router firmware will either. Now that there’s a calling for it they might add the feature but if the OS doesn’t communicate the desire to use the feature there’s not much point.
And yeah, there’s so much else that Apple Airports either can’t do or suck at doing that they aren’t worth getting. I don’t even do remote support for them, they’re so touchy feely that without sitting down in front of one there’s no way to tell what’s wrong. And the average person using one, IE a Mac tard/fanboy, isn’t the type of person that makes remote support fun and/or easy.