Are WiFi BotNets Possible?

Following from my blog about unsecured Home WiFi networks and just how widespread they are in "home user" land. I have been wondering whether it might be possible to create a kind of "WiFi BotNet".

Let’s say the attacker setup in a metropolitan area, constructed an antenna to boost the WiFi range of their device, allowing the attacker to scan and connect to any unsecured or low security WiFi networks over a significant range. Going from my own experience, there should be plenty of unsecured WiFi access points within a metro area. From this point I have two theories.

One trick could be to try and connect to several WiFi networks at the same time and create a kind of mini BotNet, perhaps by the attacker fashioning a network access point, this could provide major bandwidth and anonymity for the attacker. I need to investigate this theory further.

Or the other way, which I think could be easily possible, is to automate connecting to each unsecured WiFi network in turn, do bad stuff while connected, like send out Spam, then disconnect and move onto the next scanned unsecured WiFi access point. Again it would be almost impossible to trace back the attacker.