While most basic hardware support for GNU/Linux is improving constantly, wireless support remains dismal. Few manufacturers make an effort to support the operating system, or to publicize what support they have. Moreover, the components of wireless devices change so fast that one version of a device may offer support while a second version doesn't -- even though both versions share the same model number.
And if, in addition to functionality, you also want a device with free drivers and no reliance on proprietary firmware, your choices are even more limited. Fortunately, no matter what your preferences, online resources exist to help you find the card that's right for you or get your existing wireless network adapter to work with Linux.