Here we go...

Slack 13.1 64bit physical host, various usb wifi sticks (asus usb-n13, tenda w322u, dlink dwa140, etc...)
virtualbox 4
slack 13.1 64bit virtual machine with various usb wifi sticks assigned

So I was able to get all of them to connect to various access points with WPA2 AES 802.11n with no added drivers. Just configured /etc/rc.d/rc.inet1.conf and wpa_supplicant and /etc/rc.d/rc.inet1 restart and after a minute I'm connected.

However after a restart of the virtualised linux, the wifi shows up as a device as expected, but not connected to any access points.
Do a restart of rc.inet1 and everything come up fine.