You can use Network Manager with a static IP address.
If you want a system-wide setting, you can use
/etc/network/interfaces for a wireless adapter. The only difference with a wired adapter is that you'll need extra settings for the encryption (unless your wifi network is unencrypted).
For WPA (any supported variant), use wpa-supplicant .
iface wlan0 inet static
wpa- parameters are those you could put in a block in
For WEP, the wireless-tools package has all you need. Instead of the
wpa- settings, put
wireless- settings, e.g.