Simplest Wi-Fi connection for ATMega1280 or 328


I'd like to know about the simplest way to have Wi-Fi connection with Arduino code. I mean, something very simple like sending AT-like commands to the device (what device? Wi-Fi shield, anything else? I don't know...) in a serial connection, establishing the default Wi-Fi setting (SSID, password), and opening a connection to a remote side.

Now the second part: I would like to use FTP, only this. Any example of FTP connection via Wi-Fi + Arduino?

Thanks a lot!!!!!