My beaglebone black wasn't recognizing my wifi adapter. apt-get update ; apt-get dist-upgrade didn't help, and I noticed that it wasn't upgrading the kernel.
Looks like the way to get kernel updates is to use /opt/scripts/tools/update_kernel.sh. When I first tried it, I got errors like "The certificate of `rcn-ee.net' is not trusted".
So the first step was to "git pull" down the latest version of the update_kernel.sh script, then run it. Upon reboot, it recognized the wifi adapter.
Also note that beaglebone doesn't always do USB hotplug right, so I made sure to reboot after plugging in the adapter.
Also, even after updating the kernel, my Edimax and D-Link adapters show up but won't associate to an access point. The Keebox W150NU seems to be working well, though.
Update: Even with the W150NU, I had trouble connecting to public networks. I noticed this in dmesg: "deauthenticating from by local choice (reason=3)", which led me to a page recommending that I kill wpa_supplicant, and that fixed it.